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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
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Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 25, Issue 6 - Dec 2011
Volume 25, Issue 5 - Oct 2011
Volume 25, Issue 4 - Aug 2011
Volume 25, Issue 3 - Jun 2011
Volume 25, Issue 2 - Apr 2011
Volume 25, Issue 1 - Feb 2011
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Probabilistic Approach to Predicting Residual Longitudinal Strength of Damaged Double HullVLCC
Huynh, Van-Vu ; Lee, Seung-Hyun ; Cho, Sang-Rai ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 1~10
DOI : 10.5574/KSOE.2011.25.3.001
This paper estimates the residual longitudinal strength of a damaged double hull VLCC (Very Large Crude Carrier) under combined vertical and horizontal bending moments using Smith`s method. The damage estimated in this study occurred due to collision or grounding accidents. The effects of the randomness of the yield stress, plate thickness, extent of damage, and the combination of these three parameters on the ultimate hull girder strength were investigated. Random variables were generated by a Monte Carlo simulation and applied to the double hull VLCC described by the ISSC (International Ship and Offshore Structures Congress) 2000 report.
Experimental Study in Kinematics of Rogue Wave
Choi, Hae-Jin ; Jung, Kwang-Hyo ; Suh, Sung-Bu ; Lee, Seung-Jae ; Jo, Hyo-Jae ; Choi, Han-Suk ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 11~18
DOI : 10.5574/KSOE.2011.25.3.011
The rogue wave was generated in a two-dimensional wave tank the rogue wave kinematics was investigated including local and convective accelerations of the water particle and verification of existing prediction methods. PIV technique was applied to measure the wave kinematics near the wave crest which extended to compute the local and convective accelerations. The experimental results were compared with several analytical predictions. The convective acceleration under the crest of rogue wave has a similar magnitude with the local acceleration.
A Numerical Simulation on Three-Dimensional Hydrodynamic Characteristics of Wave Height and Flow around Asymmetric Submerged Breakwaters
Lee, Woo-Dong ; Hur, Dong-Soo ; Suh, Sung-Bu ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 19~27
DOI : 10.5574/KSOE.2011.25.3.019
In case of constructing submerged breakwaters for the purpose of preventing coastal erosion, the number of submerged breakwaters, as well as their asymmetry is dependent on the field conditions. The aim of the present study was to examine the 3-D hydrodynamic characteristics (3-D wave field, wave height, mean water level, and mean flow) around the asymmetric submerged breakwaters using a 3-D numerical model, LES-WASS-3D, which was validated through a comparison with existing experimental data and showed fairly nice agreement. From the numerical results, the wave height, mean water level, and mean flow are discussed in relation with the variation in the breakwater length ratio.
Microstructure and Thermal Shock Properties of SiC Materials
Lee, Sang-Pill ; Cho, Kyung-Seo ; Lee, Hyun-Uk ; Son, In-Soo ; Lee, Jin-Kyung ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 28~33
DOI : 10.5574/KSOE.2011.25.3.028
The thermal shock properties of SiC materials were investigated for high temperature applications. In particular, the effect of thermal shock temperature on the flexural strength of SiC materials was evaluated, in conjunction with a detailed analysis of their microstructures. The efficiency of a nondestructive technique using ultrasonic waves was also examined for the characterization of SiC materials suffering from a cyclic thermal shock history. SiC materials were fabricated by a liquid phase sintering process (LPS) associated with hot pressing, using a commercial submicron SiC powder. In the materials, a complex mixture of
powders was used as a sintering additive for the densification of the microstructure. Both the microstructure and mechanical properties of the sintered SiC materials were investigated using SEM, XRD, and a three point bending test. The SiC materials had a high density of about 3.12 Mg/m3 and an excellent flexural strength of about 700 MPa, accompanying the creation of a secondary phase in the microstructure. The SiC materials exhibited a rapid propagation of cracks with an increase in the thermal shock temperature. The flexural strength of the SiC materials was greatly decreased at thermal shock temperatures higher than
, due to the creation of microcracks and their propagation. In addition, the SiC materials had a clear tendency for a variation in the attenuation coefficient in ultrasonic waves with an increase in thermal shock cycles.
Shear and CBR Characteristics of Dredge Soil-Bottom Ash-Waste Tire Powder-Mixed Lightweight Soil
Kim, Yun-Tae ; Kang, Hyo-Sub ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 34~39
DOI : 10.5574/KSOE.2011.25.3.034
This study investigated the shear and CBR characteristics of dredge soil-bottom ash-waste tire powder-mixed lightweight soil, which was developed to recycle dredged soil, bottom ash, and waste tire powder. Test specimens were prepared with various contents of waste tire powder ranging from 0 to 100% at 50% intervals by the weight of the dry dredged soil. Several series of triaxial compression tests and CBR tests were conducted. The shear strength characteristics of the lightweight soil were compared using two different shear tests (triaxial compression test and direct shear test). The experimental results indicated that the internal friction angle of the lightweight soil obtained by the direct shear tests was greater than that by the triaxial shear tests. However, the cohesion value obtained by the triaxial shear tests was greater than that by the direct shear tests. The CBR value of the lightweight soil decreased from 35% to 15% as waste tire powder content increased.
An Experimental Study on the Sulfate Resistance of Fly Ash Antiwashout Underwater Concrete
Kwon, Joong-Hyen ; Kim, Bong-Ik ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 40~46
DOI : 10.5574/KSOE.2011.25.3.040
This paper describes the effects of fly ash replacement on the sulfate resistance of antiwashout underwater concrete which was replaced cement by fly ash from 0% to 50%. and the experimental works were performed on sulfate acceleration test of 5%
solution to find out the variance of length and weight of specimens. The experimental result shows that the length of specimens of antiwashout underwater concrete age at 180day was highly increased compare with normal concrete by acceleration test. but the mixture which was replaced 50% of fly ash shows reduction of the expansion, weight various, compare with normal concrete specimen. accordingly by using fly ash as admixture in antiwashout underwater concrete in sea environment, it will makes more durable for the attacks of sulfate by sea water.
Development of 3D Modeling System to Display the Cutting Shape of H-Beam Used in Ships and Ocean Plants
Park, Ju-Yong ; Jo, Hyo-Jae ; Lee, Ji-Hoon ; Park, Ji-Yong ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 47~52
DOI : 10.5574/KSOE.2011.25.3.047
3D geometric modeling has a lot of advantages in the field of design and manufacturing. Many manufacturing processes and production lines are using 3D geometric modeling technique. These help reduce the cost and time for manufacturing. The purpose of this study is the realization of a 3D cutting shape for an H-Beam used in ships and ocean plants. The complex 3D cutting shapes could be represented by using the boolean operation of basic figures. Graphic functions with parameters were used to simply define the basic figures. The developed system can show the complex cutting shape of an H-beam simply and quickly. This system can be utilized for the automatic cutting system for an H-beam.
Plasticity and Fracture Behaviors of Marine Structural Steel, Part III: Experimental Study on Failure Strain
Choung, Joon-Mo ; Shim, Chun-Sik ; Kim, Kyung-Su ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 53~65
DOI : 10.5574/KSOE.2011.25.3.053
This is the third of several companion papers dealing with the derivation of material constants for ductile failure criteria under hydrostatic stress. It was observed that the ultimate engineering stresses and elongations at fracture from tensile tests for round specimens with various notch radii tended to increase and decrease, respectively, because of the stress triaxiality. The engineering stress curves from tests are compared with numerical simulation results, and it is proved that the curves from the two approaches very closely coincide. Failure strains are obtained from the equivalent plastic strain histories from numerical simulations at the time when the experimental engineering stress drops suddenly. After introducing the new concept of average stress triaxiality and accumulated average strain energy, the material constants of the Johnson-Cook failure criterion for critical energies of 100%, 50%, and 15% are presented. The experimental results obtained for EH-36 steel were in relatively good agreement with the 100% critical energy, whereas the literature states that aluminum fits with a 15% critical energy. Therefore, it is expected that a unified failure criterion for critical energy, which is available for most kinds of ductile materials, can be provided according to the used materials.
Plasticity and Fracture Behaviors of Marine Structural Steel, Part IV: Experimental Study on Mechanical Properties at Elevated Temperatures
Choung, Joon-Mo ; Im, Sung-Woo ; Park, Ro-Sik ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 66~72
DOI : 10.5574/KSOE.2011.25.3.066
This is the fourth of a series of companion papers dealing with the mechanical property reductions of various marine structural steels. Even though a reduction of the elastic modulus according to temperature increases has not been obtained from experiments, high temperature experiments from room temperature to
revealed that initial the yield strength and tensile strength are both seriously degraded. The mechanical properties obtained from high temperature experiments are compared with those from EC3 (Eurocode 3). It is found that the high temperature test results generally comply with the prediction values by EC3. Based on the prediction of EC3, time domain nonlinear finite element analyses were carried out for a blast wall installed on a real FPSO. After applying the reduced mechanical properties, corresponding to
to the FE model of the blast wall, more than three times the deflections were observed and it was observed that most structural parts experience plastic deformations exceeding the reduced yield strength at the high temperature. It is noted that a protection facility such as PFP (passive fire protection) should be required for structures likely to be directly exposed to fire and explosion accident.
Plasticity and Fracture Behaviors of Marine Structural Steel, Part V: Effects of Strain Rate and Temperature
Choung, Joon-Mo ; Im, Sung-Woo ; Kim, Kyung-Su ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 73~84
DOI : 10.5574/KSOE.2011.25.3.073
This is the fifth in a series of companion papers dealing with the dynamic hardening properties of various marine structural steels at intermediate strain rates. Five steps of strain rate levels (0.001, 1, 10, 100, 200/s) and three steps of temperature levels (LT (
), RT, and HT (
)) were taken into account for the dynamic tensile tests of three types of marine structural steels: API 2W50 and Classifications EH36 and DH36. The total number of specimens was 180 pieces. It was seen that the effects of dynamic hardening became clearer at LT than at RT. Dynamic strain aging accompanying serrated flow stress curves was also observed from high temperature tests for all kinds of steels. The dynamic hardening factors (DHFs) at the two temperature levels of LT and RT were derived at the three plastic strain levels of 0.05, 0.10, 0.15 from dynamic tensile tests. Meanwhile, no DHFs were found for the high temperature tests because a slight negative strain rate dependency due to dynamic strain aging had occurred. A new formulation to determine material constant D in a Cowper-Symonds constitutive equation is provided as a function of the plastic strain rate, as well as the plastic strain level. The proposed formula is verified by comparing with test flow stress curves, not only at intermediate strain rate ranges but also at high strain rate ranges.
Basic Experiment Using Taguchi method for Vertical Wind Turbine with Wind-shield
Hong, Cheol-Hyun ; Seo, Seong-Ho ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 85~89
DOI : 10.5574/KSOE.2011.25.3.085
This study aimed to develop a wind turbine system for the domestic wind environments. The Taguchi method was applied to obtain the optimal design for a wind turbine with a wind-shield. The design parameters were defined to look for the shape of the wind turbine. Optimal parameters were determined on the basis of the analyzed level averages of the characteristics. According to the test results to which the optimal parameters were applied, the rpm improved. It was also found that a windshield 3/4 the size contributes to improving the efficiency of existing turbines.
Subsea Responses to the BP Oil Spill in the Gulf of Mexico
Choi, Han-Suk ; Lee, Seung-Keon ; Do, Chang-Ho ;
Journal of Ocean Engineering and Technology, volume 25, issue 3, 2011, Pages 90~95
DOI : 10.5574/KSOE.2011.25.3.090
On April 20, 2010, a well control event allowed hydrocarbon (oil and gas) to escape from the Macondo well onto Deepwater Horizon (DWH), resulting in an exploration and fire on the rig. While 17 people were injured, 11 others lost their lives. The fire continued for 36 hours until the rig sank. Hydrocarbons continued to flow out from the reservoir through the well bore and blowout preventer (BOP) for 87 days, causing an unprecedented oil spill. Beyond Petroleum (BP) and the US federal government tried various methods to prevent the oil spill and to capture the spilled oil. The corresponding responses were very challenging due to the scale, intensity, and duration of the incident that occurred under extreme conditions in terms of pressure, temperature, and amount of flow. On July 15, a capping stack, which is another BOP on top of the existing BOP, was successfully installed, and the oil spill was stopped. After several tests and subsea responses, the well was permanently sealed by a relief well and a bottom kill on September 19. This paper analyzes the subsea responses and engineering efforts to capture the oil, stop the leaking, and kill the subsea well. During the investigation and analysis of subsea responses, information was collected and data bases were established for future accident prevention and the development of subsea engineering.