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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 26, Issue 6 - Dec 2012
Volume 26, Issue 5 - Oct 2012
Volume 26, Issue 4 - Aug 2012
Volume 26, Issue 3 - Jun 2012
Volume 26, Issue 2 - Apr 2012
Volume 26, Issue 1 - Feb 2012
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Material Properties of Arctic Sea Ice during 2010 Arctic Voyage of Icebreaking Research Vessel ARAON: Part 2 - Compressive Strength, Flexural Strength, and Crystal Structures
Kim, Dae-Hwan ; Park, Young-Jin ; Choi, Kyung-Sik ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 1~8
DOI : 10.5574/KSOE.2012.26.1.001
To correctly estimate ice load and ice resistance for a ship's hull, it is essential to understand the material properties of sea ice during ice field trials and to use the proper experimental procedure for gathering ice strength data. The first Korean-made icebreaking research vessel (IBRV), ARAON, had her second sea ice trial in the Arctic Ocean during July and August of 2010. This paper describes the test procedures used to properly obtain sea ice strength data, which provides the basic information on the ship's performance in an ice-covered sea and can be used to estimate the correct ice load and ice resistance on the IBRV ARAON. The data gathered from three sea ice field trials during the Arctic voyage of the ARAON includes the ice compressive strength, flexural strength, and failure strain of sea ice. This paper analyzes the gathered sea ice data in comparison with data from the first voyage of the ARAON during her Antarctic Sea ice trial in January 2010.
Numerical Analysis of Free Surface Flow around Blunt Bow Ship Model
Park, Il-Ryong ; Suh, Sung-Bu ; Kim, Jin ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 9~16
DOI : 10.5574/KSOE.2012.26.1.009
This paper presents the numerical results of a simulation of the free surface flow around a blunt bow ship model and focuses on the validation of the proposed method with a brief investigation of the relation between the resistance and free surface behavior. A finite volume method based on the Reynolds Averaged Navier-Stokes (RANS) approach is used to solve the governing flow equations, where the free surface, including wave breaking,is captured by using a two-phase Level-Set (LS) method. For turbulence closure, a two equation k-
model with the standard wall function technique is used. Finally, the numerical results are compared with the available experimental data, showing good agreement.
Lowering Simulation using Floating Crane in Waves
Nam, Bo-Woo ; Hong, Sa-Young ; Kim, Byoung-Wan ; Lee, Dong-Yeop ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 17~26
DOI : 10.5574/KSOE.2012.26.1.017
A coupled analysis of a floating crane barge with a crane wire and hanging structure is carried out in thetime domain. The motion analysis of the crane barge is based on the floating multi-body dynamics, and thecrane wire is modeled as a simple spring tension. The hanging structure is assumed to be a rigid body with 3 degree-of-freedom translational motion. In this study, numerical simulations were conducted at three different stages. First, the developed code was validated by comparing the time-domain motion response of a crane barge with the frequency-domain results. Then, a coupled analysis of a crane barge and simple structure hanging by the crane wire was performed using the present scheme. The motion response and wire tension from the present calculations are compared with the results of OrcaFlex. The agreement between the two sets of results isfairly good. Last, lowering simulations in regular and irregular waves were conducted considering buoyancy changes in the hanging structure. The effects of the wave conditions, structure's weight, wire length, and lowering speed on the wire tension are considered.
Temperature Effect on Impedance-based Damage Monitoring of Steel-Bolt Connection using Wireless Impedance Sensor Node
Hong, Dong-Soo ; Kim, Jeong-Tae ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 27~33
DOI : 10.5574/KSOE.2012.26.1.027
This paper presents the effect of temperature on the impedance-based damage monitoring of steel-bolt connections using wireless impedance sensor nodes. In order to achieve the objective, the following approaches are implemented. First, a temperature-compensated damage monitoring scheme that includes a temperature compensation model and damage detection method is described. The temperature compensation model is designed by analyzing the linear regressions between the temperatures and impedance signatures. The correlation coefficient of the impedance signatures is selected as the damage index to monitor the damage occurrence in the target structures. Second, a wireless impedance sensor node is described for the design of the hardware components and embedded software. Finally, the performance of the temperature-compensated impedance-based damage monitoring scheme is evaluated for detecting a loose bolt in the steel-bolt connections on a lab-scale steel girder under various temperatures.
Experimental Modal Analysis for Damage Identification in Foundation-Structure Interface of Caisson-type Breakwater
Lee, So-Young ; Lee, So-Ra ; Kim, Jeong-Tae ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 34~40
DOI : 10.5574/KSOE.2012.26.1.034
This paper presents an experimental modal analysis of a caisson-type breakwater to produce basic information for the structural health assessment of a caisson structure. To achieve the objective, the following approaches are implemented. First, modal analysis methods are selected to examine the modal characteristics of a caisson structure. Second, experimental modal analyses are performed using finite element analyses and lab-scale model tests. Third, damage scenarios that include several damage levels in a foundation-structure interface are designed. Finally, the effects of damage on the modal characteristics are analyzed for the purpose of utilizing them for damage identification.
Taguchi Robust Design of Tracked Vehicle for Manganese Nodule Test Miner in Collecting Operation Considering Deep-sea Noise Factors
Cho, Su-Gil ; Lee, Min-Uk ; Lim, Woo-Chul ; Choi, Jong-Su ; Kim, Hyung-Woo ; Lee, Chang-Ho ; Hong, Sup ; Lee, Tae-Hee ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 41~46
DOI : 10.5574/KSOE.2012.26.1.041
A deep-sea manganese nodule miner consists of 4 parts: the pickup device, crusher, disposal device, and tracked vehicle. The tracked vehicle is an essential component to keep the self-propelled miner moving across deep-sea soil. The performances of the tracked vehicle are influenced by noise factors: the shear strength of the seafloor, bottom current, seafloor slope, track speed, reaction forces of flexible hose, etc. It is necessary to adopt a robust design method that improves the performances and minimizes the variation caused by noise factors. Taguchi's method, the most widely known robust design method, searches for the robust optimum using an orthogonal array composed of the product of the inner array and outer array. In this paper, we propose a new screening technique to reduce the number of input factors and apply the MRSN (Multi-Response Signal to Noise) ratio to convert multiple performances into single one in order to overcome the difficulties and limitations of using Taguchi's method in a case with many input factors and multiple performances. A test miner was already designed and tested. It has about 1/10 the capacity of a commercial one and was successfully operated at an in-shore area. Taguchi's robust design was applied to the tracked vehicle of the test miner, and design improvements were implemented for the vehicle.
VRS-GPS Measure of Typhoon Surge Flood Determinedin Busan Coastal Topography
Kim, Ga-Ya ; Jung, Kwang-Hyo ; Kim, Jeong-Ho ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 47~53
DOI : 10.5574/KSOE.2012.26.1.047
A coastal flood area was predicted using the empirical superposition of the typhoon surge level and typhoon wave height along the Busan coastal area. The historical typhoon damages were reviewed, and the coastal topography was measured using VRS-GPS. A FEMA formula was applied to estimate the coastal flood area in a typhoon case when the measured and predicted data of typhoon waves are not available. The results in the area of Haeundae beach and Gwangalli beach were verified using the flood area data from the case of Typhoon Maemi (2003). If a Hurricane Katrina class typhoon were to pass through the Maemi trajectory, the areathat would be flooded along theBusan coastal area was predicted and compared with the results of the Maemi case. Because of the lack of ocean environment data such as data for the sea level, waves, bathymetry, wind, pressure, etc., it is hard to improve the prediction accuracy for the coastal flood area in the typhoon case, which could be reflected in the policy to mitigate a typhoon's impact. This paper discusses the kinds of ocean environment information that is needed to predict a typhoon's impact with better accuracy.
A Study on Ullage Effect in 2-D Sloshing Experiment
Choi, Hu-In ; Kwon, Sun-Hong ; Lee, Sang-Beom ; Lee, Ki-Hyun ; Park, Jung-Ho ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 54~59
DOI : 10.5574/KSOE.2012.26.1.054
This study presents investigation on ullage effect in sloshing experiment. The experiment was done with two dimensional tank. Sloshing experiments were carried out in the tank with 6 different ullage pressures. The tested filling ratio was 30% of the tank height. The flow field was recorded with high speed camera. The sloshing impact pressure were measured at 18 locations. It was shown that the variation of ullage pressures influences the magnitude of pressure and flow field. This study demonstrated the importance of ullage pressure in sloshing test.
Estimation of Environmental Costs Based on Size of Oil Tanker Involved in Accident using Neural Network
Shin, Sung-Chul ; Bae, Jeong-Hoon ; Kim, Hyun-Soo ; Kim, Seong-Hoon ; Kim, Soo-Young ; Lee, Jong-Kap ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 60~63
DOI : 10.5574/KSOE.2012.26.1.060
The accident risks in the marine environment are increasing because of the tendency to build faster and larger ships. To secure ship safety, risk-based ship design (RBSD) was recently suggested based on a formal safety assessment (FSA). In the process of RBSD, a ship designer decides which risk reduction option is most cost-effective in the design stage using a cost-benefit analysis (CBA). There are three dimensions of risk in this CBA: fatality, environment, and asset. In this paper, we present an approach to estimate the environmental costs based on the size of an oil tanker involved in an accident using a neural network. An appropriate neural network model is suggested for the estimation,and the neural network is trained using IOPCF data. Finally,the learned neural network is compared with the cost regression equation by IMO MEPC 62/WP.13 (2011).
Optimization of Friction Welding for Motor Vehicle Safety Belts: Part 1-Mechanical Properties and Microstructure
Kong, Yu-Sik ; Ahn, Seok-Hwn ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 64~69
DOI : 10.5574/KSOE.2012.26.1.064
Dissimilar friction welds were produced using 15-mm diameter solid bars of chrome molybdenum steel (KS SCM440) and carbon steel (KS SM20C) to investigate their mechanical properties. The main friction welding parameters were selected to ensure good quality welds on the basis of visual examination, tensile tests, Vickers hardness surveys of the bond area and HAZ, and macro-structure investigations. The specimens were tested as-welded and post-weld heat treated (PWHT). The tensile strength of the friction welded steel bars was increased to 100% of the SM20C base metal under the condition of a heating time of more than four seconds. Optimal welding conditions were n = 2,000 (rpm), HP = 60 (MPa), UP = 100 (MPa), HT = 5 (s),and UT = 5 (s), when the total upset length was 7.8 (mm). The hardness distribution peak of the friction welded joints could be eliminated using PWHT. The two different kinds of materials were strongly mixed to show a well-combined structure of macro-particles, with no molten material, particle growth, or defects.
Numerical Analysis of Offshore Installation Using a Floating Crane with Heave Compensator in Waves
Nam, Bo-Woo ; Hong, Sa-Young ; Kim, Jong-Wook ; Lee, Dong-Yeop ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 70~77
DOI : 10.5574/KSOE.2012.26.1.070
In this study, a numerical analysis of offshore installation using a floating crane with heave compensator is carried out in time domain. The motion analysis of crane vessels is based on floating body dynamics using convolution integral and the crane wire is treated as simple spring. The lifted structure is assumed as a rigid body with 3 degree-of-freedom translational motion. The heave compensator is numerically modelled by the generalized spring-damper system. Firstly, forced motion simulations of crane wire system are carried out to figure out the basic principle of heave compensator. The transfer function of crane wire system is obtained and effective wave period of heave compensator are found. Then, coupled analysis of crane vessel, crane wire, and lifted structure are performed in regular and irregular sea conditions. Two different crane vessels and two lifted structures (suction pile and manifold) are considered in this study. Through a series of numerical calculations, the effective zone of heave compensator is investigated with respect to wave period and crane wire length.
Key Technologies for Floating Type Artificial Upwelling System to Strengthen Primary Production
Jung, Dong-Ho ; Lee, Ho-Saeng ; Kim, Hyeon-Ju ; Moon, Deok-Soo ; Lee, Seung-Won ;
Journal of Ocean Engineering and Technology, volume 26, issue 1, 2012, Pages 78~83
DOI : 10.5574/KSOE.2012.26.1.078
The abundant nutrients contained in deep seawater are delivered by natural upwellings from the deep sea to the surface sea. However, the natural upwelling phenomenon is limited to specific areas of the sea; in other areas, the thermocline separates the surface sea from the lower layer. Thus, the surface layer is often deficient in nutritive salts, causing the deterioration of its primary productivity and ultimately leading to an imbalance in the marine ecosystem. Without a consistent supply of nitrogenous nutritive salts, they are absorbed by phytoplankton, resulting in a considerable problem in primary productivity. To solve this issue, a floating type of artificial upwelling system is suggested to artificially pump up, distribute, and diffuse deep seawater containing rich nutritive salts. The key technologies for developing such a floating artificial upwelling system are a floating offshore structure with a large diameter riser, self-supplying energy system, density current generating system, method for estimating the emission and absorption of CO2, and way to evaluate the primary production variation. Strengthening the primary production of the sea by supplying deep seawater to the sea surface will result in a sea environment with abundant fishery resources.