In the offshore wind project off the coast of Iwafune, offshore wind turbines are installed in a general sea area. After authors carefully conducted the consensus building on the project, Murakami city council and the inter-agency council decided to promote the project. Besides, a project promotion committee was set up in Murakami city by the municipal ordinance in order to publicly seek the developer for carrying out a valid feasibility study on the project. In the project promotion committee, an assessment committee was also set up and devised the procedure manual for the feasibility study. Murakami city put out an open call for developers following the procedure manual for the feasibility study. After the assessment committee selecting the developer from several applicants, the project promotion committee confirmed the developer for the project. The selected developer entered into discussion with the parties concerned in order to carry out the feasibility study.

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 The purpose of this research is to establish the stand-alone power generation system by means of wind power generation in ports and coastal area. It is necessary to know the variance characteristics of demand of electric power in port facilities. This paper shows investigated data of electric power usage in a port that is located at the west coast of Hokkaido and northern part of Kyushu. The differences of demand and supply by wind generation and hybrid system with solar generation and storage battery are analyzed and the countermeasures to reduce the energy gap of demand and supply also discussed.

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 This paper introduces necessity and importance of utilization of the International Technical Certification Scheme, for the safe and successful offshore wind farm projects. In Japan, there is a strong expectation for offshore wind farm because of its huge Exclusive Economic Zone by overcoming Japanese sever meteorological condition, for example typhoon, earthquake, tsunami and lightning. Regarding wind turbines, IEC has been developing various inter-national standard and certification scheme, which we should utilize for the sake of safety and stability of wind farm business.

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 The GPS ocean wave meter (GPS buoy) has been installed at 18 sites around Japan for NOWPHAS(The Nationwide Ocean Wave information network for Ports and HArbourS) of Ports and Harbours Bureau, Ministry of Land, Infrastructure, Transport, and Tourism, it measures ocean waves in the offshore. The unit installed some 20 kilometers off the coast of Kamaishi City, Iwate Prefecture, measured the tsunami triggered by the Great East Japan Earthquake of 2011 and helped the Japan Meteorological Agency to update its tsunami warnings. To ensure early detection of tsunami, it is necessary to install it farther than the existing GPS buoy. However, the existing GPS buoy can be only installed within some 20 kilometers from the coast, because the real-time kinematic (RTK) method and wireless data transmission was adopted. This paper reports the summary of the new GPS ocean wave meter and the demonstration experiments for hydrographic phenomenon in the offshore.

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 Typhoon is one of the most devastating meteorological phenomena causing storm surge disaster. Recently, some researchers reported that typhoons will be stronger and their courses will shift toward the east or/and the north due to global warming. Therefore, it is of great importance to investigate the characteristics of future typhoons. In order to predict the potential storm surge due to the future typhoons, the climate projection data seem to be useful. In this study, especially focusing on the typhoon courses, we investigated the change of typhoon characteristics due to global warming around Japan by comparing the future climate data with the present climate data computed by MRI-AGCM3.2S. First, we extracted typhoon data from the time series of atmospheric pressure data around Japan. Next, we analyzed the passing number and each central pressure of the typhoons which passed every latitude. Then we investigated the characteristics of spatial distribution of passing number and strength of typhoons. We also compared the median point of typhoon tracks in the future with that at the present. As results, it is found that there is no significant change in the mean typhoon course, although unevenness in typhoon courses will be slightly bigger in the future than at the present. It is also found that the area over which strong typhoons pass through, i.e., around Okinawa as seen in the present climate data, tends to spread in all the directions in the future climate.

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 The low pressure with rapid development generated storm surge and inundation over a port and city in Nemuro. The aims of this paper are to provide the information of storm surge height measured by the authors and to clarify the generation mechanism of the storm surge. Based on the authors' field survey, the maximum storm surge height at the street and the port in Nemuro was approximately 2.20 m and 2.80 m, respectively. Furthermore, the ground level in Nemuro decreased from coastal line toward the street. According to the numerical results with WRF and FVCOM, the water level in Nemuro bay increased at first because of the East wind. Then, the mass of water intrudes to the Nemuro Peninsula because of north wind and caused the storm surge. In conclusion, the local topography of Nemuro, the direction changes of wind and the topography of Nemuro Peninsula caused the damage of the storm surge to Nemuro.

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 In order to conduct a coupling between a wave equation and the Navier-Stokes equation, the vertical distribution of horizontal velocities should be estimated at the connection boundary of them with the variables calculated in the wave equation. The FFT method which is applied to the wave train obtained only after wave calculation can be used to that, though it requires larger number of component waves to approximate the original wave train with higher wave nonlinearity. In this paper, a new method, which estimates the vertical distribution of horizontal velocities under wave calculation, is proposed with applying each nonlinear wave theory to approximation of the variables of wave calculation respecting relative water depth. And an applicability of a one-way coupling from NOWT-PARI to CADMAS-SURF is verified.

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 A series of field observation of ship waves consist of wave observation and visual one has been carried out in Ishigaki port. The wave observation is continuous observation for 3 days by using five wave gages. The visual observation is also conducted to obtain information ships navigating in the port. By analyzing the observation data, it is confirmed that (1) ship waves amplify the waves in Ishigaki port, (2) wave height, period, and direction of ship waves are quantitatively obtained, and (3) wave reflection coefficients against ship waves for vertical wall and breakwater with wave dissipating blocks take smaller value than those against general waves.
 The observation result also indicates that ship waves generated in the port is a possible factor to make the calmness worse even if the port is adequately protected from ocean waves.

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 Wave absorbing mounds are constructed on the harbor sides of the breakwaters for reduction of reflection of long-period waves. Armor units of wave absorbing mounds constructed on the harbor sides have to be stable for wave overtopping. In this study, the stability of the armor units of wave absorbing mounds constructed on harbor sides of sloping top breakwaters and rectangular ones for wave overtopping are compared by hydraulic model experiments. The armor units of wave absorbing mounds with the sloping top breakwaters are more unstable than with the rectangular ones. When the crest of the wave absorbing mound is higher than water surface, armor units are more unstable than when the crest is the same height as the water surface. But in this case, the transmission coefficient of overtopping wave is smaller than in case of submerged mounds.

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 This study investigates two effective measures that reduce a wave overtopping at the joint corner between flaring shaped seawall and upright one. One is an overhanging on the crown of the flaring shaped seawall, and the other is the bulkhead on the seawall section. Hydraulic experiments are carried out with a plane basin. This study confirmed that the overhanging section effectively reduces the wave overtopping at the joint corner. The bulkhead with slits improves the function of the overhanging. The overhanging with bulkhead reduces the wave overtopping rate less than the case of straight levee normal of the seawall. This countermeasure also reduces the wave overtopping at the joint corner on the upright seawall side. The maximum wave pressures on the overhanging and bulkhead are less than two times of hydrostatic pressure corresponded to an incident wave height. The pressure distributions are similar on each section. No impulsive wave pressure profiles can be observed on the overhanging and bulkhead.

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 In "Sanyo District" of Shimonoseki Port Coast, shore protection against overtopping by stormy waves and overflows by storm surge are required due to the geographical features of low land less than high tide level. The projects implemented so far are composed mainly of coastal revetments with additional sluice gate, land gate, a drainage pumping station and others. In these projects, operation system for maintenance of the project facilities and reduction of the construction cost were issues to be settled. Therefore, the shore protection works are reviewed and examined from the view of life cycle cost of construction and maintenance of the facilities.

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 This study discusses the change in cross sections of bodies when artificial reefs made of crushed stones of mixed particle diameter are subjected to irregular waves. The author has found that the distribution of the frequency spectrum of transmitted waves depends on crushed stones constituting bodies. For a body consisting of one type of crushed stone, a larger deposition area of the crushed stone was found at the back of the crest of an artificial reef with smaller R. Under the same wave condition, the crushed stone No. 7 (S-5) of the erosion area of a body flows toward the onshore. However, the crushed stone No. 5 (S-20) of the erosion area of a body does not flow. These results show that the particle diameter and mass of crushed stones affect the stability of bodies.

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 The design method of scour protection around the cooling water outlet was shown with the example of an outlet which will be constructed at the sea bottom in front of the Ishikariwan-Shinko LNG power plant. The combination of 2-D and 3-D wave simulation using CADMAS-SURF gave the flow distribution and maximum flow velocity around the outlet. The covering blocks should be put on the area where the flow is accelerated by the existence of the outlet. The Isbash's equation showed the required weight of the covering blocks.

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 The characteristics of drag coefficient of a vertical surface piercing cylinder in inundation flow are studied. The drag forces acting on the test cylinders in inundation flow of open channel were measured by using a multi component load cell in steady and unsteady flow were measured. The pressure distributions around the test cylinder were measured by using static-pressure measurement in steady flow. The time variation of typical principal velocity and water depth of coming inundation flow were also measured exactly by using a Laser Doppler anemometer and wave gages. The drag coefficient of the test cylinders decreases with increase of Froude number of uniform flow. The decrease of C_d with increase of instantaneous Froude number of coming flow is also appeared in unsteady flow like a dam braking flow. These phenomena may be due to the decrease of water surface depth appearing in wake of the test cylinder.

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 This study deals with the computation methods for drag force of permeable layer in the numerical wave flume CADMAS-SURF. Two models using the drag coefficient and Dupuit-Forchheimer law are available to compute the drag force in CADMAS-SURF. The reflection coefficient and overtopping quantity are taken as the evaluation indices, and the numerical computations and laboratory experiments are conducted using regular waves and a conventional revetment that consists of rubble or wave-dissipating blocks to investigate the applicability of the models. It is shown that the numerical results obtained from the model using Dupuit-Forchheimer law agree reasonably well with the experimental data.

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 Wave energy devices installed in the real ocean change the physical environment around the site to affect morphological and biological conditions by interacting with the incident waves and other devices. The final goal of this study is to build a model to predict deformation of irregular waves around a wave energy device that can be applied on a wave prediction model so that we can evaluate effects of a wave energy project on the physical environment around. The present study performed laboratory experiments to understand basic characteristics of the wave deformation around a simplified model of a floating oscillating water column (OWC) wave energy device which is known to be robust for severe wave conditions and can be installed offshore having more powerful wave resources. Relationship between the peak frequency of the incident waves and wave frequency for the peak energy absorption of the OWC model was found to determine the wave spectrums of the transmitted and reflection waves.

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 The detailed wave estimation was conducted for the safety of the tidal current power facilities in Goto Islands, Nagasaki Prefecture. The wave estimation database and the numerical coastal wave model SWAN were applied for the long-term wave estimation efficiently. Furthermore, the estimation results were compared with the neighboring wave observation data and some revision was made to improve the precisions.

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 Six private companies and research institutes & universities jointly started a consortium research for practical use of the oscillating water column system (OWC) in 2011. Projecting-walls (PW), installed both side of the opening, were found out to make frequency dependency reduced. At the same time, hydraulic experiment for the single OWC facility installed on the line of breakwater showed sudden drop down of the efficiency of the primary conversion against a certain wave period. This occurred due to the interposition with reflection waves from the ambient surface of breakwater. Reduction of wave reflection improved this drop significantly.
 The consortium with 2 new members tried a new application of PW-OWC system to the existing coastal embankment in the Sakata Port. The line of this embankment shows no bad effect of reflection waves, as the embankment has a series of two air chambers in front-back direction inside to reduce wave-reflection. An experiment facility of wave power conversion was finally installed on this embankment in December, 2014. After the official safety inspection by METI, the field experiment was started to obtain the data of waves and generated electricity since January, 2015. The PW-OWC system installed on the existing facility is expected a possible design of the practical application

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 The tidal currents around Amami-oshima Island were examind in relation to tidal current power generation using the results of ADCP Observation and numerical simulation. We fonud the tidal current power of 1.5 kW/m² in the Oshima Strait and 1.7 kW/m² in the Yorojima Channel. Moreover, it was shown from the numerical simulation for the case of arrayed 20 tidal current turbines in the Oshima Strait that the daily mean value of extractable tidal energy is 19 MW and the amplitudes of tidal currents are reduced about 20 %.

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 Characteristics in variations of power potential of the Kuroshio were examined using the output data from MOVE/MRI.COM developed by the Japan Meteorological Agency. As a result, it was shown that the power potential is large in the western regions of Taiwan and Amami-oshima, and in the southern regions of Shikoku, Kii Peninsula and Boso Peninsula. Approximately 10-20% (5-10%) of variation of the potential in their regions is caused by the interannual (seasonal) variation. In addition, it was shown that the potential in the southern regions of Kii Peninsula and Boso Peninsula is large during the period of the large meander path of the Kuroshio. Moreover, we clarified the time length required to calculate the mean value of the potential based on the results of MAPE.

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 Tidal current energy is one of the promising ocean renewable energies to help Japan from energy shortage. The straits around Goto Islands in Nagasaki Prefecture are well known as the high tidal current velocity area and therefore are good candidate for the demonstration field and the prospective commercial tidal farm.
 The field surveys of the tidal current, the bathymetry, etc. were conducted at the Experimentation Fields set by Nagasaki Prefecture in Naru Strait and Tanoura Strait. Numerical simulation was also conducted for modeling the tidal current and the tidal energy features during a year, and the results were validated with the measured data. High tidal currents exist in both straits with the peak current velocity exceeding 2.7 m/s at the spring tide to generate 1MW by a planned tidal turbine. High current energy density areas suitable for the installation of turbines were confirmed in overall consideration of the tidal current energy and the sea bottom conditions.

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 In the floating offshore wind turbine demonstration project funded by the Ministry of the Environment, a spar-type floating offshore wind turbine equipped with a 2MW wind turbine has been installed offshore Kabashima, Goto city, and the offshore test has been carried out since October 2013. For structural design of the facility, the design loads have been determined from the response analysis results in time domain based on dynamic simulations for storm and power generation conditions. In this paper, an overview of the structural design of the facility such as how to set the design natural environment conditions, design load cases, load analysis method used in the structural design, structural analysis technique, fatigue analysis, mooring analysis, etc., is introduced.

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 The authors have been developing a new method for offshore wind resource assessment, which uses surface meteorological measurements from a buoy and a mesoscale model-simulated vertical wind speed profile to estimate hub-height wind speed. In this study, this buoy-simulation hybrid method is verified using surface and LIDAR measurements obtained on the pier of the Hazaki Oceanographical Research Station (HORS). It is found that when wind comes from a sea sector, the estimation accuracy is comparable to that found for an open ocean in previous studies. However, the accuracy of a 1-D model becomes considerably worse for winds coming from a land sector, and a 3-D mesoscale model (WRF), which can take effects of atmospheric stability and horizontal advection into account, is required to estimate offshore winds with an acceptable accuracy.

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 For the purpose of considering an optimal use of Four Dimensional Data Assimilation (FDDA) in the Weather Research and Forecasting model (WRF) simulations, this study investigates the impacts on the accuracy of estimated offshore wind speeds by testing six different FDDA settings for two domains. The most optimal settings, found in this study, are that 1) all the layers in the first domain should be assimilated and 2) the atmospheric boundary layer should be excluded from FDDA in the second domain.

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 This paper introduces results of field study using the offshore observation tower system constructed off the Kita-Kyusyu city, aiming to clear-up the influence of wave characteristics for the rational design of offshore wind turbine support structures. It was shown that fluctuations of normal offshore winds were affected by waves and thermal conductions from sea surface. The idea of rational combination of abnormal wind and wave actions was shown by Inverse First-order Reliability Method (IFORM).

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 JPower has been advancing the “Offshore Meteorological Observation System Experimental Research” project(offshore from Kitakyushu City) as NEDO's contractor from FY 2009 to FY 2016 and the “Offshore Wind Power Generation System Experimental Research” project(offshore from Kitakyushu City) as NEDO's joint researcher from FY 2011 to FY 2016.
 Access for Offshore Wind power facilities is more hard than Onshore Wind Power because it is influenced by wave. And then it is necessary to predict wave condition accurately in order to do maintenance Offshore Wind power efficiently and safely. This paper introduces summary and validity of the wave prediction system and actual condition of access.

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 Pile supported wharf is a framed structure which supports the superstructure of RC with a steel pipe pile. Design of pile supported wharf is conducted based on the assumption that load is not transmitted to the framed structure from the earth retaining because it is thought to be advantageous for the seismic performance of the wharf. However, validity of the assumption has not been examined thoroughly thus far. In this study, two dimensional finite element earthquake response analysis modeling pile supported wharf is conducted. As boundary condition between framed structure and earth retaining, both independent condition and fixed condition were considered. The result of the analysis showed that it is not necessarily advantageous to apply the independent boundary condition. It was found that difference between the horizontal and vertical displacement of the wharf and earth retaining greatly affect the advantageous boundary conditions.

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 Pile supported wharf is a framed structure which supports the superstructure of RC with a steel pipe pile. Major damage mechanism of the wharf is the occurrence of the plastic hinge in the piles. As the close technical field survey is required for the evaluation of the damage level of the piles, it is difficult to judge the serviceability of the wharf just after the earthquake.
 This study discusses the evaluation method of the degree of damage of pile supported wharf by earthquake focusing the natural period of the wharf. In this study, two dimensional finite element earthquake response analysis modeling pile supported wharf is conducted. As the result, natural period of the wharf becomes approximately 1.2 times longer when plastic hinge occurs in the pile.

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 It is urgently necessary to achieve seismic retrofit of energy-related facilities in waterfront area against large-scale earthquakes in the near future, such as Nankai Trough earthquake and Tokyo inland earthquakes. During earthquakes the following requirements are needed in an open-type wharf with marine loading arms; 1) reduction of acceleration response to prevent damage to loading arms, 2) reduction of displacement response to prevent damage to piping, 3) prevention of damage of steel pipe piles to keep stability of a wharf. To satisfy these requirements, an application study of buckling-restrained braces has been carried out. It has been found that effective damping effect is obtained by placing the buckling-restrained braces between the wharf and new foundations whose horizontal rigidity is higher than the wharf.

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 The objective of this study is to analytically clarify the effect of steel bar corrosion on the seismic performance of the entire pile-supported structure, and to then propose an appropriate maintenance method for pile-supported structures with steel bar corrosion, based on the analytical results.
 First, a steel corrosion model using RC beams was proposed and verified. Then, the structural performance of the corroded RC beams was analyzed. Concurrently, loading experiments of the RC beams were conducted to verify the analyses. After confirming the validity of the analysis, the constitutive law of RC beams with various corrosion patterns was calculated by cyclic loading analysis. The seismic performance of the pile-supported structure with several combinations of this constitutive law was analyzed to clarify the relationship between local steel bar corrosion and the seismic performance of the whole structure. Finally, an appropriate maintenance method was proposed based on the analytical results.

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 Recently, seabed resources development is focused. Concrete is one of the materials to construct sea platform to mine seabed resources. However, the knowledge is not enough to use concrete under high water pressure. So this research aims to verifying the applicability of concrete under high water pressure. It was shown that the difference in pore structure due to the difference in water-cement ratio or air content influenced the strain change and fracture behavior of cement paste and mortar specimens under high water pressure.

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 There is little information of waves far from coastal zones currently, the possibility of wave information is studied here by using a wave radar analyzer and numerical simulation models, WRF and SWAN. It is assured that measured wave data is practically enough accurate to apply for ship operation. On the other hand, computed results in numerical models underestimate wave heights a little. It is necessary to accumulate wave data in many ships from now on, and it will help to correct wave height accurately. The wave information service far from coastal areas is expected to construct.

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 Considering the fact that navigation channels were blocked by drifting objects at ports in northeast Japan at the East Japan Great Earthquake, one part of Waterways to be Developed and Preserved in Tokyo Bay (Central Navigation Channel of Tokyo Bay) was largely expanded so that vessels can safely take refuge in the event of tsunami attacks on Tokyo Bay. On the other hand, as the said expanded water area was originally utilized for refuge for typhoons, the effectiveness of the area as typhoon refuge needs to be confirmed once again.
 In this study, vessel behavior was compared between the case of tsunami and typhoon, focusing upon time series transition of number of vessels and size of anchorage area per vessel, in order to evaluate whether or not the said water area can be also safely utilized as refuge in the event of typhoons.

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 Authors constructed the basis of navigational system and sea navigation for safety of a sailing small boat in coastal sea areas in a bay and a port. Therefore, in order to evaluate the simulation and navigation systems authors have developed, a questionnaire is conducted toward the third grade students of navigvigational course of Faculty of Maritime Science, Kobe University. In the questionnaire, the navigation, bathymetric and meteorology information of the navigational simulation and the sea navigation supplied by the simulation and real-time navigational system are evaluated by the presentation of the images recorded during the experiments. It is confirmed that the navigational simulation and the sea navigation are very effective. Also, many effective comments to two system were obtained.

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 While very large bulk carriers are built in order to respond to the rapid growth of demand by developing countries and the Panama Canal Expansion, an initiative called international strategic port policy has been implemented. However, planning method of navigation channel design for bulk carriers under reduced draft has not been developed. Based on the above, as a first step toward the future development of such planning method, this paper is aiming at analyzing vessel motions under reduced draft, by applying the detailed designing methods adopted in the 2007 Technical Standard of Port Facilities.

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 In recent years, processing capacity is tight at container terminals of the ports while security measures have been strengthened in maritime transport and port areas. Meanwhile, the three-item check (checks on the ID, organization and purpose of entrance) was made mandatory on July 1, 2014.
 In this study, because the traffic jam aggravation by the three-item check was concerned, I surveyed the actual situation of the container terminals. At the surveyed terminal, the aggravation of the traffic jam by the three-item check was not confirmed.
 If strengthening security measures increased the processing time of the in-coming container trailers by five minutes, the present gate equipment would overflow. But multi-staging the gating process could prevent overflow. I was able to confirm the possibility that a gating process could promote efficiency by the multi-staging gating process.

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 In marine works, it is important to get wave prediction results for safety operation and work executable judgment. Recently, the advanced wave prediction method using the WAM model has been utilized generally in marine works. However, the accuracy of the wave prediction results is not clear in marine work conditions.
 In this study, we observed field wave around reef area, and constructed of the wave prediction model composed the WAM model (offshore) and an energy balance equation (onshore). From the comparison with the model prediction results and the wave measurement results, we discussed the accuracy of the wave prediction results for marine works around the reef area. As a result, the wave prediction model can estimated precisely the wave height at the coastal wave gauge site, but sometimes differ between before and after the wave direction changes.

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 The performance requirement for marina varies depending on the quality of the service. In previous approaches, a limit wave height 0.3m or less is usually applied as service limit in the existing marina. On the other hand, when wave height is less than 0.3m, the rolling and pitching of floating pier may give uneasiness to users depending on the natural period of the floating pier and harbor.
 In this study, I examined application of restrictions of marina by the rolling and pitching of the floating pier. First, I suggested that even if it was less than wave height 0.3m we feel uneasiness when ascending and descending the stairs. Second, the field observation on the marina clarified properties of the floating pier and wave. Survey on the use of marina confirmed the service limit of the floating pier. Finally, the improvement of calmness that adapted to the properties showed an effect.

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 In the Great East Japan Earthquake, flotsam was scattered around ports after the tsunami. Consequently, immediate elimination of obstacles in shipping routes by work ships was needed to recover port logistics. However, the work ships themselves suffered much damage in the tsunami. This is because, prior to the tsunami, the damage estimation of the work ships had not been taken into consideration. In the current state of the tsunami disaster countermeasures, there is a possibility that the work ships won't survive the tsunami or won't be ready for use. Therefore, as an initial step toward the development of tsunami countermeasures for work ships, it is necessary to consider safety of the work ships that will be responsible for early restoration of port functions. In this study, the behavior characteristics of work ships that were moored in port in the tsunami were revealed by a unified analysis of tsunami propagation simulation and ship response simulation. In this paper, the interest was mainly focused on the breaking of mooring lines. Also, an effective location for shelter was revealed through numerical verification by evaluating the tsunami risk of the actual mooring area.

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 While a type of marine turbine for tidal current generation can be chosen from several types, a vertical axis marine turbine (VAMT) should be better in Japan because current velocity around Japanese islands is not sufficient. This study conducted a sea test of a VAMT of a floating type which installed with six straight pitch-controllable blades. The cycloidal mechanism was adapted for the pitch control. The purpose of the study is to understand effects of ocean waves and motion of a floating body on the performance of the VAMT not in ideal current conditions. Besides, the data taken should be effective to consider that effects in order to design VAMTs. The setup with the setting angle of -30 degrees suggested highest performance from the sea tests, then 15% in maximum turbine power and maximum output was 40W. Ocean waves strongly affected on the turbine performance because fluid velocity changes due to ocean waves and it was unable to neglect the variation of the velocity in spite of small. The characteristics of the turbine sensitively varied because of ocean waves. The results suggests that during accelerating and decelerating incoming fluid speed, characteristics of the turbine were different in each case.

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 In marine constructions, it is the most crucial to evaluate motions of working vessels, in order to ensure safety and improve construction accuracy. Assuming real situations in which a breakwater and another vessel exist around the working vessel, dynamic response analyses for multiple bodies were carried out.
 The computed results showed that the motions of the working vessel might be larger than those obtained by the dynamic response analyses for the working vessel only. Therefore, under real situations in marine constructions, dynamic response analyses considering multiple bodies should be used.
 Combining the results of the dynamic response analyses with NOWPHAS data, a new method to evaluate operating ratio was proposed.

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 In this study, we made an attempt to clarify the influence of sea ice on wind waves in Sea of Okhotsk by using sea ice area and sea ice volume data sets estimated from stellite images. The Ekman spiral was confirmed to control the differene of the directions between wind and wave from the meteorological data and wave direction data in the coastal area of Sea of Okhotsk. It was found from sea ice and wave height data that the more the sea ice exists, the less the wave height is induced, especially, in the southern part of Sea of Okhotsk. In addition, sea ice volume is revealed to be more influencial compared to sea ice area by using the simple model equations proposed in this study. As one of the most significant results, when there is no sea ice in winter season, significant wave height is found to become more than twice as large as the case when sea ice exists the greatest.

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 Previous studies demonstrated that sea ice contains as much nutrients as natural riverine water, which suggests that sea ice can bring nutrients from the northern to southern part of the Sea of Okhotsk by freezing riverine water. Therefore, sea ice is considered to transport nutrient to the southern part of the Sea of Okhotsk. However, sea ice that comes along the coastal region of the Sea of Okhotsk is revealed to decrease due to the climate change. This study thus aims to investigate how sea ice is transported by using satellite images. The proposed method was able to estimate the transfer vector of sea ice.

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 Sea ice always moves in the up-and-down direction under the influence of a tide. If the conditions, that could remove rust layers, are as usual in the field, larger wear of steel in ice-infested sea compared to ice-free sea must be considered in the design of steel structures. The sliding wear test in a low-temperature chamber was carried out to examine the conditions of removing rust layers, using corroded steel specimen with rust layers in contact with saline ice. The contact pressure, grain size and amount of sand at the interface were taken as paramaters here to understand corrosive wear in the ice-infested sea. This research leads to the prediction of the deterioration of steel in ice-infested sea, using the obtained results and environmental conditions in-situ, and the relation of elapsed year to corrosion amount.

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 Recently, traffic hindrances due to wave overtopping frequently occur at coastal railways close to the seawall. In this paper, track bed damages of a coastal railway facing to the sea of Japan were investigated, and the countermeasures were proposed based on the results of hydraulic experiments. The characteristics of wave pressure distribution behind the seawall were examined by wave overtopping experiments using random waves under the scale of 1/40. It was shown that wave overtopping occurs when the offshore wave height becomes higher than 4.0m. Based on the time series of wave pressure obtained by wave overtopping experiments, wave action was also reproduced by water falling experiments in the scale of 1/4. The track bed facilities, such as ballast, rail and wood crossties, were modeled in the experimental channel. The ballast scouring due to wave overtopping was reproduced by the falling water related to the offshore wave height. The relationship between the ballast damage ratio and the offshore wave height was disclosed for the typical storm wave conditions. As for the countermeasures against the ballast damage, the effect of installing a net on the track bed and construction of the upright wall was revealed based on the experimental results.

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 In recent times, coastal roads have been increasingly hit by high waves, and this is attributed to climate change and subsequent rises in sea levels. Accordingly, road embankments have been damaged more often than ever. In this study, we investigated cases of such damage on the Okhotsk coast of Hokkaido, and we identified the threshold for wave damage on coastal roads with 1:10 longitudinal slope. It was defined to be 60 m from the shoreline toward the embankment. We also examined the factors contributing to embankment damage and preventive measures by performing a hydraulic model experiment. From the experiment, the conditions of damaged sites were reproduced by expressing the run-up height of the wave, a causal factor of damage, as R_2%. Similarly, the swash velocity (u) was found to be related to the thickness of the water layer (η) to experiment the threshold of the causal factors of damage to road embankments. Damage was estimated to occur when u_2% = 0.6 m/s and η_2% = 0.9 m. In the end, we examined the effectiveness of immediate and permanent measures against coastal road embankment damage.

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 We investigated the beach changes in shoreline area of the Hasaki coast with the boundary conditions as a pocket beach bounded by both reclaimed land of Kashima Port and Hasaki fishing port breakwater. In this area, southward longshore sand transport was predominant in the wave-shelter zone of the fishing port breakwater, whereas northward longshore sand transport prevailed far from the fishing port, which was supposed to be southward in the previous study. Thus, the reversal of the direction of longshore sand transport occurred on the coast.

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 In the Bisan-seto strait channel and the surrounded area, there are many sand waves which are consecutive sand bank of several meters of wave height and tens of meters of wave length. The sand waves cause the channel trouble by the water depth becoming shallow locally. In this study, the prediction model of sand wave growth is developed in the given external condition of the water depth, the current velocity and the bottom grain size. The base of the sand wave model is an analytical technique for stability theory of the dune. As the conditions of limiting growth of sand waves, underwater angle of repose of sediments and continuity of sediment movement at the trough are set. As a result, the expressions of the displacement velocity and the growth rate of sand waves are obtained. Referring to the existing investigation results of the displacement velocity, wave height and wavelength of sand waves, the parameter included in the expressions are decided.

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 On the Shimizu coast, L-shaped groins have been planned to control longshore sand transport without damaging the scenery of Mt. Fuji from the shoreline. Also, detached breakwaters have been constructed to prevent beach from eroding. When storm waves hit the coast, large beach changes would occur, and these beach changes are important in considering the plan of L-shaped groins. Therefore, beach changes triggered by storm waves during Typhoon Nos. 16 and 27 in 2013 were investigated on the Shimizu coast. It was found that the wave dissipating effect of the detached breakwaters was reduced during storm waves, and cuspate forelands formed behind the structures were eroded.

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 The shoreline changes in the merginal area of the Banzu tidal flat were investigated by using aerial photographs and field investigations. The area immediately north of the Obitsu River mouth was eroded due to the spatial imbalance of longshore sand transport, and sand was transported to form a sand spit at the mouth of the north tributatry of the Obitsu River. The longshore sand transport rate was estimated to be 127 m³/yr at the site. Furthermore, the barrier top was moved landward by 7 m on average owing to the overflow of the 2011 Great Tsunami.

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