권호 표지

Journal of Ocean Engineering and Technology (한국해양공학회지)

Korean Society of Ocean Engineers (한국해양공학회)

  • Bimonthly
  • /
  • 1225-0767(pISSN)
  • /
  • 2287-6715(eISSN)

Domain

  • Construction/Transportation ＞ Maritime Safety/Transportation Technology
  • Construction/Transportation ＞ Water Engineering System

Aim & Scope

Journal of Ocean Engineering and Technology provides a medium for the publication of original research and development technology in marine/material science and engineering which include: Ocean Engineering; Coastal Engineering; Naval Architecture; Offshore Technology; Frontier Energy Resources Technology; Marine Renewable Energy; Underwater Vehicles and Robotics; Underwater Acoustics and Sonar Technology; Underwater Observation Systems; Underwater Communication and Technology; Marine Equipments; Remote Sensing of Air/Ocean Surface; Ocean Mining; Offshore Mechanics; Marine Hydrodynamics and CFD; Sloshing Dynamics and Design; Vortex-induced Vibration; Cable, Mooring, Buoy Technology; Fluid-Structure Interaction; Hydroelasticity; Risk and Limit State Design and Assessment; Ship Maneuvering; Seakeeping and Control Systems; Ship Resistance and Propulsion; Port and Waterfront Design and Engineering; Geotechnology; Satellite Observation; Shore Protection; Beach Nourishment; Sediment Transport; Mechanics; Safety and Reliability; Subsea; Pipelines; Risers and Positioning; High-Performance Materials; Nano-technologies for Clean Energy; Friction Stir Welding for Oil and Gas; Arctic Materials; Arctic Science and Technology; Advanced Ship Technology; Naval and Offshore Structures and Technology; and Oceanography.

http://www.joet.org KJCR IF:0.331(2017)

Volume 33 Issue 2

  1. Choi, Sol-Mi;Lee, Jaeyong;Lee, Seung Jae;Lee, Daesoo;Jung, Kwang-Hyo 99
    https://doi.org/10.26748/KSOE.2018.098 PDF
    Unlike typical a dynamic positioning (DP) system, a DP-assisted mooring system must determine a set point (SP) that can ensure a mooring tension safety range to prevent an excessive increase in mooring tension. In this paper, a new algorithm for determining the SP is suggested in order to reduce the tension on all the mooring lines. To determine the SP, a working area around the vessel is represented by a rectangular grid. Thus, the size of the grid area is limited considering the offset of a vessel with a mooring system. At each grid's nodes, the resultant tension from all the mooring lines is estimated using the time history of the tension and vessel's position. The results of static analyses for each grid position are used to estimate the global tension. Consequently, the SP is automatically selected as a position satisfying criterion for minimizing the total tension. In order to validate the suggested algorithm, a motion simulation with the control system in the time domain and a discussion of the results are presented.
  2. Cho, Il-Hyoung 106
    https://doi.org/10.26748/KSOE.2018.095 PDF
    The interaction between a sloshing liquid damper (SLD) tank and a rectangular pontoon was investigated under the assumption of the linear potential theory. The eigenfunction expansion method was used not only for the sloshing problem in the SLD tank but also for analyzing the motion responses of a rectangular pontoon in waves. If the frictional damping due to the viscosity of the SLD tank was ignored, the effect of the SLD appeared to be an added mass in the coupled equation of motion. The installation of the SLD tank had a greater effect on the roll motion response than the sway and heave motion of the pontoon. One resonance peak for rolling motion showed up in the case of a frozen liquid in the SLD tank. However, if liquid motion in the SLD tank was allowed, two peaks appeared around the first natural frequency of the fluid in the SLD tank. In particular, the peak value located in the low-frequency region had a relatively large value, and the peak frequency located in the high-frequency region moved into the high-frequency region as the depth of the liquid in the tank increased.
  3. Kim, Dongeun;Poguluri, Sunny Kumar;Ko, Haeng Sik;Lee, Hyebin;Bae, Yoon Hyeok 116
    https://doi.org/10.26748/KSOE.2019.023 PDF
    Among the various wave power systems, Salter's duck (rotor) is one of the most effective wave absorbers for extracting wave energy. The rotor shape is designed such that the front part faces the direction of the incident wave, which forces it to bob up and down due to wave-induced water particle motion, whereas the rear part, which is mostly circular in shape, reflects no waves. The asymmetric geometric shape of the duck makes it absorb energy efficiently. In the present study, the rotor was investigated using WAMIT (a program based on the linear potential flow theory in three-dimensional diffraction/radiation analyses) in the frequency domain and verified using OrcaFlex (design and analysis program of marine system) in the time domain. Then, an experimental investigation was conducted to assess the performance of the rotor motion based on the model scale in a two-dimensional (2D) wave tank. Initially, a free decay test (FDT) was carried out to obtain the viscous damping coefficient. The pitch response was extracted from the experimental time series in a periodic regular wave for two different wave heights (1 cm and 3 cm). In addition, the viscous damping coefficient was calculated from the FDT result and fluid forces, obtained from WAMIT, are incorporated into the final response of the rotor. Finally, a comparative study based on experimental and numerical results (WAMIT & OrcaFlex) was performed to confirm the performance reliability of the designed rotor.
  4. Jung, Jae-Hwan;Oh, Seunghoon;Nam, Bo-Woo;Park, Byeongwon;Kwon, Yong-Ju;Jung, Dongho 123
    https://doi.org/10.26748/KSOE.2018.079 PDF
    The flow around a curved riser exposed to the current in various directions was investigated at a Reynolds number of 100 using a numerical simulation. The present study found that the flow features of the curved riser were distinct from those of a straight riser as a result of its large radius of curvature. Namely, there were various wake patterns according to the flow's incident angle. As the incident angle increased from $0^{\circ}$ to $90^{\circ}$, a two-row street of vortices that developed along the centerline of the curved riser became more apparent. However, when the incident angle approached $180^{\circ}$ from $90^{\circ}$, these vortices were completely suppressed by the interaction between the wake and an axial flow induced by the curvature of the riser. To identify this feature, the sectional force coefficients were also considered, and it was found that the force coefficients could be different from those found in a sectional analysis based on the strip theory when investigating vortex-induced vibration. As a result, this kind of study would be important to realistically estimate the riser VIV (vortex-induced vibration) and fatigue life, and a new force coefficient database that includes the three-dimensional effect should be established.
  5. Kim, Min-Gyu;Jung, Kwang-Hyo;Park, Sung-Boo;Lee, Gang-Nam;Park, Il-Ryong;Suh, Sung-Bu 131
    https://doi.org/10.26748/KSOE.2019.009 PDF
    This study focused on the roll motion characteristics of a two-dimensional (2D) rectangular floating structure under regular beam sea conditions. An experiment was conducted in a 2D wave tank for a roll free decay test in calm water and the roll motion in a range of regular waves with and without heave motion to investigate the motion response and heave influence on the roll motion. A numerical study was carried out using Reynolds-averaged Navier Stokes (RANS)-based CFD simulations. A grid convergence test was conducted to accurately capture the wave condition on the free surface based on the overset mesh and wave forcing method. It was found in the roll free decay test that the numerical results agreed well with the experimental results for the natural roll period and roll damping coefficient. It was also observed that the heave motion had an impact on the roll motion, and the responses of the heave and roll motion from the CFD simulations were in reasonable agreement with those from the experiment.
  6. Cho, Hee-Joo;Kim, Sung-Hoon;Choi, Jungho 139
    https://doi.org/10.26748/KSOE.2019.005 PDF
    It is important that an MGO Chiller System, which is one of the sulfur oxide emission control technologies, is designed to meet the fuel temperature requirements, even with sudden engine load changes. Three different control algorithms (PI, Cascade, and MPC) were applied to an indirect MGO chiller system to compare and analyze the outlet temperature dynamic characteristics of the system through a case study. The results showed that the MPC control method had the best temperature following characteristics in the case study, and the temperature deviation range was reduced by approximately 5% compared to the PI control method.
  7. Ham, Juh-Hyeok 146
    https://doi.org/10.26748/KSOE.2018.032 PDF
    A design system was developed for the doubler plate of a ship structure simultaneously subjected to in-plane loads and lateral pressure based on general dimensions and those of a representative ship structure. An equivalent design equation that considers various structural design parameters was derived by introducing the equivalent plate thickness theory, and the design of the doubler plate reinforcement of the ship structure was developed. A hybrid structural design system was established for a doubler plate simultaneously subjected to in-plane loads and lateral pressure consisting of two modules: an optimized design module and a double plate strength & design review module. The practical application of this design system was illustrated to show its usability. It was found that the design safety of the doubler plate was ensured, and this system could be used as an initial design guide to review the double plate reinforcement for a dent or corrosion of the ship plate members. Using the developed design system would make it possible to obtain a more reasonable doubler plate structure that considers the rational reinforcement of plate members of ship structures. In addition, a more reliable structural analysis using a strength evaluation process can be performed to verify the efficiency of the optimum structural design for the doubler plate structure.
  8. Lee, Dong-Hun;Seo, Jung-Kwan;Yi, Myung-Su;Hyun, Chung-Min 153
    https://doi.org/10.26748/KSOE.2019.011 PDF
    Welding often results in welding distortion during the assembly process. The welding distortion of thin-plate structures such as the living quarters of ships and offshore installations is a more significant problem than in the case of thick-plate structures. Pre-stressing/heating and fairing, which are additional works to mitigate and control welding distortion, are inevitable, and the construction planning is accordingly delayed. In order to prevent welding distortion and minimize the additional work during the assembly process, increasing the plate thickness and/or the number of stiffeners may be a simple solution, but it may give rise to problems related to cost and weight. In this study, the welding distortion control effect of the type of stiffeners on the door openings of various living quarter structures was investigated using an experimental method and a finite element method. The results showed the feasibility of mitigating and controlling the welding distortion, and the optimum selection of the type of stiffeners was confirmed.
  9. Cho, Sungrok;Choi, Kyungsik 161
    https://doi.org/10.26748/KSOE.2019.013 PDF
    This paper focuses on a newly designed ice load formula based on the ARAON's 2016 Arctic field data in order to improve a structural design against ice loads. The strain gage signals from ARAON's hull plating were converted to the local ice pressure upon the hull plating using the influence coefficient matrix and finite element analysis. First, a traditional pressure-area relationship is derived by applying probabilistic approaches to handle the strains measured onboard the ARAON. Then, the local ice load prediction formula is re-analyzed after reviewing the ARAON's additional field data to consider information about the ship speed and thickness of the sea ice. It is shown that the newly developed pressure-area relationship well reflects the influence of other design parameters such as the ship speed and ice thickness in the prediction of local ice loads on Arctic vessels.
  10. Yeu, Taekyeong;Choi, Hyun Taek;Lee, Yoongeon;Chae, Junbo;Lee, Yeongjun;Kim, Seong Soon;Park, Sanghyun;Lee, Tae Hee 168
    https://doi.org/10.26748/KSOE.2019.021 PDF
    KRISO (Korea Research Institute of Ship & Ocean Engineering) started a project to develop the core algorithms for autonomous intervention using an underwater robot in 2017. This paper introduces the development of the robot platform for the core algorithms, which is an ROV (Remotely Operated Vehicle) type with one 7-function manipulator. Before the detailed design of the robot platform, the 7E-MINI arm of the ECA Group was selected as the manipulator. It is an electrical type, with a weight of 51 kg in air (30 kg in water) and a full reach of 1.4 m. To design a platform with a small size and light weight to fit in a water tank, the medium-size manipulator was placed on the center of platform, and the structural analysis of the body frame was conducted by ABAQUS. The robot had an IMU (Inertial Measurement Unit), a DVL (Doppler Velocity Log), and a depth sensor for measuring the underwater position and attitude. To control the robot motion, eight thrusters were installed, four for vertical and the rest for horizontal motion. The operation system was composed of an on-board control station and operation S/W. The former included devices such as a 300 VDC power supplier, Fiber-Optic (F/O) to Ethernet communication converter, and main control PC. The latter was developed using an ROS (Robot Operation System) based on Linux. The basic performance of the manufactured robot platform was verified through a water tank test, where the robot was manually operated using a joystick, and the robot motion and attitude variation that resulted from the manipulator movement were closely observed.
  11. Cho, Gun Rae;Kang, Hyungjoo;Lee, Mun-Jik;Li, Ji-Hong 178
    https://doi.org/10.26748/KSOE.2019.010 PDF
    When burying underwater cables using robots, heading control is one of the key functions for the robots to improve task efficiency. This paper addresses the heading control issue for URI-T, an ROV for underwater construction tasks, including the burial and maintenance of cables or small diameter pipelines. Through modeling and identifying the heading motion of URI-T, the dynamic characteristics and input limitation are analyzed. Based on the identification results, a PD type controller with appropriate input treatment is designed for the heading control of URI-T. The performance of the heading controller was verified in water tank experiments. The field applicability of the proposed controller was also evaluated through the sea trial of URI-T at the East Sea, with a water depth of 500 m.
  12. Yu, Young-Jae;Sim, Woo-Lim;Kumar, Rupesh;Kim, Dong-Ju;Shin, Hyun-Kyoung 189
    https://doi.org/10.26748/KSOE.2018.038 PDF
    In this study, experiments with a floater using flapping foils were performed to develop a new station keeping system that can maintain its position in waves without mooring lines. The foils applied to this system generate thrust using wave energy. In this experiment, the motion of the floater was analyzed in three different wave periods. Sixteen foils were attached to the cylindrical floater. The thrust of each foil was controlled by changing its azimuth angle, and three cases were compared. Based on the previous data, we made more precise measurements and found an optimal model for stationkeeping under each wave condition. We verified the potential of this new stationkeeping system using flapping foils, and conclusions were drawn from the results.
  13. Shin, Yunkil 196
    https://doi.org/10.26748/KSOE.2019.016 PDF
    In this study, the excessive noise and vibration phenomena of a high-speed Ro/Ro passenger ship were analyzed, and a countermeasure was taken based on them. This ship was granted a comfort class notation by the classification society, which was COMFORT-VIBRATION-II and COMFORT-NOISE-CREW-II. However, unfortunately, excessive noise and vibration in the aft part of the ship were delivered from the twin shaft propellers, and therefore the Class Requirement was not satisfied before delivery. In order to obtain the class notation, all of the concerned parties came to an agreement to reduce the noise and vibration level during operation after delivery because a seasonal ferry service was already scheduled and the cabin was fully booked. The root cause of the massive amount of noise and vibration was mainly the propeller-induced excitation pulse and beating that occurred from the mismatch of the rotating speeds of the two shaft lines. A 1st order vibrating force and beating phenomena existed in the propeller. Thus, a reduction of the excitation force, elimination of the beating phenomena, and decrease of the noise level at the aft area cabins and public spaces were required. In addition, structural reinforcements were conducted using pillars and additional girders at the aft part of the decks.
  14. Kim, In-Chul;Park, Ki-Chul 203
    https://doi.org/10.26748/KSOE.2018.084c1 PDF