The SPE has split the former "Management & Information" technical discipline into two new technical discplines:
- Data Science & Engineering Analytics
The SPE has split the former "Management & Information" technical discipline into two new technical discplines:
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ABSTRACT Currently, the number of the fishing vessel in the world is very large. The studies related to cargo ships, tankers or large ships are more carried out than fishing vessels. Moreover, the fishing vessel operates for a long time at one position in the sea for exploiting fish. Thus, it is crucial to observe the effect of the irregular wave on the ship's motion. The purpose of this study is to investigate the ship motion in the irregular waves by performing the model test. The model test of the Russian trawler was performed in the square wave tank at Changwon National University in various wave directions at zero speed. An Optical-based system was used to measure the six degrees of freedom (6DOF) motion of the ship. Firstly, the motion responses of the ship in the irregular waves in various wave directions are investigated. The time histories of the ship motion response are transferred to the frequency domain from the time domain. Secondly, the effect of the wave frequency component on the ship motion responses is analyzed. The natural frequency of the ship and peak of the wave frequency have strong responses on the motion spectrum in irregular waves. Finally, the effect of the wave direction on the ship motion spectrum is discussed. INTRODUCTION Nowadays, the number of fishing vessels increase rapidly due to increased fishing demand. In addition, the fishing vessel operates for a long time at one position in the sea for drop and drag the net. The ship motions are affected by environmental conditions i.e. wind, wave, current… However, the wave is the most effect on the ship motion. Therefore, it is necessary to predict the ship motion in sea conditions. In the part, it has much research studied the ship motion in irregular waves. Shen, Ye and Wan (2014) predicted the ship motion response in irregular waves using URANS simulations. In their study, the ship motion responses in the irregular waves were compared by using the numerical method, experimental method and strip method. Jiao and Huang (2020) investigated the seakeeping performance of the S175 container ship by using CFD simulation. The results of ship motion responses in regular waves and cross waves were compared. This study discovered that the transverse and heave motion response in the cross waves can be large from those in the regular waves. Im and Lee (2021) investigated the effect of tonnage on the motion response of fishing vessel in regular waves. The ship motion responses were performed on different sizes of fishing vessel by using numerical method. Mainum, Yaakob, Kamal and Wei (2006) estimated the motion spectral of the Malaysian fishing vessel using operation data. The ship motion and wave elevation were measured by vessel motion monitoring system and the wave buoy. Hence, the motion spectral and response amplitude operator were obtained. Nurhasanah, Santoso, Romadhoni and Nasutioni (2020) predicted the response amplitude operator and spectral response in heave, roll and pitch motion by using strip theory calculation (Maxsurf software). The effect of rounded hull, double chine and multi chine on ship motion responses were investigated. Sivabalan and Sivakumar (2020) calculated the ship motion responses of the fishing vessel in various wave directions. The ship motion response were carried out in regular waves and irregular waves using potential flow (MOSES software). Lee, Choi, Ahn, Kim, Kim and Shighehiro (2015) studied the ship motion responses in irregular waves. The ship motion responses in irregular waves were obtained based on strip method in regular waves and using linear superposition theory to estimate the energy spectrum. Ghamari, Greco, Faltinsen and Lugni (2020) investigated the heave, roll and pitch motion of a fishing vessel by performing numerical method and experimental method with and without forward speed in regular waves. The results of the ship motion response of numerical and experimental method were compared.
Nguyen, Van Minh (Changwon National University) | Nguyen, Tien Thua (Changwon National University) | Seo, Juwon (Changwon National University) | Yoon, Hyeon Kyu (Changwon National University) | Kim, Yeon Gyu (Korea Research Institute of Ships & Ocean Engineering)
ABSTRACT In the past, traditional methods of research on ship maneuvering performance were estimated in calm waters. However, the course-keeping ability and the maneuvering performance of a ship can be influenced by the presence of waves. Therefore, it is necessary to understand the maneuvering behavior of a ship in waves. In this paper, the prediction force acting on the rudder in calm waters was carried out and compared with those of CFD. Model test in regular wave was performed to predict the force acting on the ship and the rudder behind the model ship in various wave directions. INTRODUCTION In the past, traditional methods of research on ship maneuvering performance was estimated in calm waters conditions was not associated with seakeeping performance. The course-keeping ability and the maneuvering performance of a ship can be dramatically affected by the real sea condition. Therefore, it is necessary to understand the maneuvering behavior of a ship in waves in the viewpoint of ship safety in the design stage. According to ITTC (2008), the ship maneuverability in waves is of vital importance for navigation safety of seagoing ships. Various researchers have investigated the maneuverability of a ship in waves. Adnan and Yasukawa (2006) measured the added resistance, steady drifting lateral force and yaw moment acting on an obliquely moving ship in regular waves using the S-175 container ship model. Xu et al. (2007) conducted an experimental research on ship maneuverability in waves which included a series of a Planar Motion Mechanism (PMM) tests in waves to measure the forces on the model. Skejic et al. (2008) developed the unified theory of seakeeping and maneuverability of ships in regular waves. Seo and Kim (2011) explored the numerical analysis on ship maneuvering coupled with ship motion in waves. These researchers only mentioned the ship maneuverability in waves in the case of head sea, and beam sea, but they did not evaluate the influence of incident wave which poses the real challenge in the maneuverability of the ship. In this study, the force and yaw moment acting on a moving ship in regular waves with different wavelength and wave direction was performed in the square wave tank in Changwon National University (CWNU). First, experiments on forces and moment were conducted in waves and calm waters using the KCS container ship model. In addition, to verify the force acting on the rudder in calm waters, the comparison of the experiment of force acting on the rudder in calm waters between EFD and CFD was carried out. Second, forces and moment were obtained by subtracting the experiment results in waves from the results obtained in calm waters. Finally, the effect of wavelength and wave direction on the forces and moments acting on the ship hull was discussed. The force and yawing moment acting on the rudder behind KCS model versus rudder angle in various wave directions were investigated in detail.
Kim, Jong-Kyu (Department of Ocean Engineering, Yosu National University Hydro Environment Research Institute, GeoSy stem Research Corporation) | Kang, Tae-Soon (Department of Ocean Engineering, Yosu National University Hydro Environment Research Institute, GeoSy stem Research Corporation)
ABSTRACT To explain and simulate the coastal circulation, it is necessary to develop the three dimensional ocean circulation model in the south-eastern coastal water of Korea. The open boundary conditions are evaluated from the tidal observation data obtained from the open boundary. This model represented well the flow pattern through the tidal phase. Especially, it showed that the reversing time of tidal currents in the surface level are delayed for about half an hour with respect to the bottom. This phase lag between the surface and the bottom is considered to be attributed to the inertial force of the flow in coastal waters. Based on the investigation, the tidal currents are accelerated with the corresponding components of wind direction and are decelerated with the opposite direction. Also, the flow pattern of the bottom level showed a compensative flow, which is an important mechanism of vertical circulation in coastal waters. INTRODUCTION Recently many enclosed basins have problems in water quality and the environmental managements to solve it have been conducted. The Chinhae Bay and Pusan Port which are located in the southern eastern coastal waters of Korea and have such problems, like Fig. 1. The Chinhae Bay with surface area of 680 km2 is connected with the southern coastal waters by two narrow and shallow channels. Therefore, the exchange of sea water in the bay with the outer sea is inefficient. Since pollutants produced by urban and industrial complexes are discharged into the bay, significantly decrease in the self-purification capacity of sea water in the bay poses a serious environmental and social concern. A large scale underwater sewage outfall for citizens of more than one million in Masan and Changwon city is under construction. Massive reclamation and construction projects along the coast are under planning.
Ikushima, Yutaka (Tohoku National Industries Research Institute) | Kurata, Y. (Tohoku National Industries Research Institute) | Hatakeda, K. (Tohoku National Industries Research Institute) | Kim, H. (Tohoku National Industries Research Institute) | Son, M. (Tohoku National Industries Research Institute)
ABSTRACT The corrosion behavior of constituent metals (Fe, Cr, Mo) of iron-base and nickel-base alloys has been examined in 5 mass% NaCI at temperatures of 300-450 °C and at a constant pressure of 30 MPa. The mass changes of pure Cr are very small in the range of 300 to 450 °C and their magnitude is close to the limit of detection, whereas pure Fe and Mo show significant mass losses at temperatures of 300 to 450 °C. The mass loss of pure Fe is higher than that of pure Mo at 300-350 °C, but is lower at 400-450 °C. The oxide films on pure Fe, Cr, and Mo consist of Fe304 and 7-Fe203, Cr203, and MoO2 and MOO3, respectively. The surfaces of pure Cr were homogenous and blue in color, but no trace of corrosion. The surfaces of pure Fe were covered with a thick oxide film by the treatment at temperatures of 300 to 450 °C. Pure Mo grew up to be uniform oxide layer with a needle-like shape with increasing temperature. INTRODUCTION Supercritical water oxidation (SCWO) is a promising and very effective method for destruction of hazardous organic wastes t-4. The physicochemical properties of water have been studies at low and high densities, and thermodynamic properties are known to change widely with pressure and temperature 5. 6, for example, the static dielectric constant, e=80 for the liquid phase, decrease to the range of about 3-20 in the supercritical region 7, and so nonpolar organic compounds are very soluble or miscible in supercritical water (SCW). This nature along with J Present address: Battery Research Group, KERI, Changwon 641-120, Korea high diffusivity and low viscosity is expected to function as an ideal medium for the oxidation of organics in the presence of oxidants and result in several advantages over conventional processes such as incineration. On SCWO process any organics can be rapidly and completely oxidized to harmless compounds and inorganic species can be separated 2, 3, 8, 9. However, SCWO process is performed at high temperature and pressure in a medium containing an oxidant and other corrosive inorganic species. Therefore, this environment leads to a severe corrosion of reactor materials like stainless steels 10, 11, nickel-base alloys ~2-~9 and most of the ceramic materials 20-22 To develop SCWO as a practical technology, it is absolutely essential to overcome corrosion problems of reactor materials. Most investigations have been done with iron-base 10,, and nickel-base alloys 12-19 on the corrosion of materials in sub- and supercritical water oxidation environments. Tebbal et al. 10 reported that type 316-L stainless steel may exhibit the corrosion resistance in the pH 2 to 11 region and in the low concentration ranges of reactive halide ions (e. g. F, CI, Br). Boukis et al. 13. 15. z8, ~9 examined the corrosion behavior of Ni-base alloys in aqueous solutions containing hydrochloric acid and oxygen under sub- and supercritical conditions. They found that the corrosion of the Ni-base alloys are dependent on the dissociation of the attacking acid, the temperature, the solubility of the corrosion products, and the electrochemical potential of the solution. The results of the previous studies suggest that the corrosion behavior of iron-base and nickel-base alloys is strongly dependent of environmental factors. Furthermore, the corrosion behavior of iron-base and nickel-base alloys is affected by alloy composition ~7, 18. Boukis et al. ~8 have reported the corrosion behavior of Ni-base alloy 625 (UNS N06625) and its main constituents (Ni, Cr, and Mo) in HC1 solutions in the presence of oxidants at 350 °C and 24 MPa. According to their report, Ni showed strong degradation and Mo was dissolved completely after a reaction time of 5 hours. The corrosion of Cr started at grain