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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 21, Issue 6 - Dec 2007
Volume 21, Issue 5 - Oct 2007
Volume 21, Issue 4 - Aug 2007
Volume 21, Issue 3 - Jun 2007
Volume 21, Issue 2 - Apr 2007
Volume 21, Issue 1 - Feb 2007
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Wave Forces Acting on Vertical Cylinder and Their Wave Transformations by 3-Dimensional VOF Method
Lee, Kwang-Ho ; Lee, Sang-Ki ; Sin, Dong-Hoon ; Kim, Chang-Hoon ; Kim, Do-Sam ;
Journal of Ocean Engineering and Technology, volume 21, issue 2, 2007, Pages 12~21
As the economy grows and the population increases, we need to develop our coastal area and make use of it for various purposes. Specifically, investigation of the wave interactions on and around the vertical cylinders is very important in the design of the offshore or coastal structures. The nonlinear potential analysis developed so far, although very useful, has been found to be limited in application, as strong nonlinear waves generated by the interference between multilayered cylinders and wave impact forces by breaking waves can hardly be estimated. In this study, using a 3-Dimensional volume tracking method VOF(Volume of Fluid), based on Namer-Stokes equations, was developed to simulate highly nonlinear effects, such as breaking waves at the interface or complicated interference waves among structures. A numerical method for nonlinear interaction wave and vertical cylinders is newly proposed. The wave forces and wave transformations computed by the newly proposed numerical simulation method were compared to the other researcher's experimental results, and the results agree well. Based on the validation of this study, this numerical method is applied to the two vertical cylinders to discuss their nonlinear wave forces and wave transformations, according to the variations of separate distance of vertical cylinders.
Delta Development in the Nakdong River Estuary: a Literature Survey
Yoon, Han-Sam ; Yoo, Chang-Ill ; Kang, Yoon-Koo ; Ryu, Cheong-Ro ;
Journal of Ocean Engineering and Technology, volume 21, issue 2, 2007, Pages 22~34
We present basic data for developing new research topics and closely examine the existing data on the development and organization of the Nakdong River Estuary Delta by analyzing various studies of the area, including ocean engineering, coastal engineering, ocean environmental engineering, geomorphological, and geological studies. We first defined the general concepts related to the estuary and delta and reviewed the historical development of the Nakdong River Estuary Delta over the past 100 years. We then examined the origin and core elements of the estuary deposits that constitute the delta. In addition, we scrutinized the main factors affecting the development of the delta and analyzed existing research on delta development mechanisms by core researchers. The construction of an estuary barrage is one of the main factors effecting estuarine circulation and has altered the physical oceanic environment, area of deposition, atmospheric environment, and vegetation community of the delta. These factors affect the estuary circulation in turn, altering the delta. Along the Nakdong River, an unsteady-state sandy barrier appears at approximately three times the distance of the wavelength of incident offshore waves, and this terrain forms approximately 10-15 years after reclamation in the interdistributary upper stream and transforms the shoreline. It is necessary to develop a technique to predict terrain change that reproduces the erosion and accumulation of estuarine deposits. To determine the parameters and variables necessary to reproduce this system, continuous on-site monitoring is necessary. The existing research did not fully examine the terrain changes in Nakdong River Estuary or the periodic developmental characteristics. To understand the future process of estuary delta development, it is necessary to establish an integrated management system.
Inundation Analysis Considering Water Waves and Storm Surge in the Coastal Zone
Kim, Do-Sam ; Kim, Ji-Min ; Lee, Gwang-Ho ; Lee, Seong-Dae ;
Journal of Ocean Engineering and Technology, volume 21, issue 2, 2007, Pages 35~41
In general, coastal damage is mostly occurred by the action of complex factors, like severe water waves. If the maximum storm surge height combines with high tide, severe water waves will overflow coastal structures. Consequently, it can be the cause of lost lives and severe property damage. In this study, using the numerical model, the storm surge was simulated to examine its fluctuation characteristics at the coast in front of Noksan industrial complex, Korea. Moreover, the shallow water wave is estimated by applying wind field, design water level considering storm surge height for typhoon Maemi to SWAN model. Under the condition of shallow water wave, obtained by the SWAN model, the wave overtopping rate for the dike in front of Noksan industrial complex is calculated a hydraulic model test. Finally, based on the calculated wave-overtopping rate, the inundation regime for Noksan industrial complex was predicted. And, numerically predicted inundation regimes and depths are compared with results in a field survey, and the results agree fairly well. Therefore, the inundation modelthis study is a useful tool for predicting inundation regime, due to the coastal flood of severe water wave.
Estimation of Ability for Water Quality Purification Using Ecological Modeling on Tidal Flat
Shin, Bum-Shick ; Kim, Kyu-Han ;
Journal of Ocean Engineering and Technology, volume 21, issue 2, 2007, Pages 42~49
It has been known that shallow-water regions, such as tidal flats, sea grass and sea weed beds have water purification capability, and they also serve as nursery grounds for many fishes. On the other hand, tidal flat areas are economically attractive sites for reclamation, to be used for developing industries. When developing shallow-water areas, we have to propose a plan to mitigate the environmental impact associated with such a development plan. However, it is difficult to estimate the affects on the ecosystem and water purification, and the literature related to this matter is insufficient. In order to evaluate the ability of coastal tidal flat and to predict the future changes, it is necessary to develop a reliable prediction technique and construction of data by using a field investigation. In this study, we carried out a numerical model test for the tidal flat ecosystem, using the pelagic system and the benthic system, simultaneously, in order to show a change in the tidal flat ecosystem. The flow of nitrogen, phosphorus and carbon has been identified as a primary consideration of marine ecosystem components, and the capability of water purification and the change of the tidal flat were predicted using this flow. In order to make a more reliable prediction, a field investigation to determine tide, current and creatures of the object coastal area has been done. The purification capability of this shallow-water region is estimated from the model results. According to the results of experiments, the tidal flat has a capability of water purification (Sink) of 11mgN/m2/day, but the other area has a load (Source) of 20mgN/m2/day. As a result, we could confirm that the tidal flat of an object coastal area plays an important role in water purification.
Failure Assessment and Strength of Steam Generator Tubes with Wall Thinning
Seong, Ki-Yong ; Ahn, Seok-Hwan ; Yoon, Ja-Moon ; Nam, Ki-Woo ;
Journal of Ocean Engineering and Technology, volume 21, issue 2, 2007, Pages 50~59
Steam generator tubes are degraded from wear, stress corrosion cracking, rupture and fatigue and so on. Therefore, the failure assessment of steam generator tube is very important for the integrity of energy plants. In the steam generator tubes, sometimes, the local wall thinning may result from severe degradations such as erosion-corrosion damage and wear due to vibration. In this paper, the elasto-plastic analysis was performed by FE code ANSYS on steam generator tubes with wall thinning. Also, the four-point bending tests were performed on the wall thinned specimens, and then it was compared with the analysis results. We evaluated the failure mode, fracture strength and fracture behavior from the experiment and FE analysis. Also, it was possible to predict the crack initiation point by estimating true fracture ductility under multi-axial stress conditions at the center of the thinned area from FE analysis.
Standardization of Ice Mechanics Experimental Procedures in a Cold Room
Kim, Jung-Hyun ; Choi, Kyung-Sik ; Seo, Young-Kyo ;
Journal of Ocean Engineering and Technology, volume 21, issue 2, 2007, Pages 60~66
The first Korean cold room facility for ice mechanics experiments was assembled in 2004. Since then, the
cold room facility has been used, extensively under various environmental and loading conditions. After reviewing published references on cold room testing methods and also by trial and error, the standard procedures for testing and preparing laboratory ice material were established for the measurement of basic ice properties. In this paper, laboratory experimental techniques with the cold room facility and standard procedures established for ice material properties are introduced. Test specimens include laboratory-grown fresh water ice and frozen soils. Tests are carried out for unconfined compressive strength. Preparation and dimension of the specimen are the most important issues arising in cold room tests. The details of specimen preparation, testing procedure and strength test results are also discussed.
Development and Tank Test of an Autonomous Underwater Vehicle 'ISiMI'
Jun, Bong-Huan ; Park, Jin-Yeong ; Lee, Pan-Mook ; Lee, Fill-Youb ; Oh, Jun-Ho ;
Journal of Ocean Engineering and Technology, volume 21, issue 2, 2007, Pages 67~74
Maritime and Ocean Engineering Research Institute (MOERI), a branch of KORDI, has designed and manufactured a model of an autonomous underwater vehicle (AUV) named ISiMI (Integrated Submergible for Intelligent Mission Implementation). ISiMI is an AUV platform to satisfy the various needs of experimental test required for development of challenging technologies newly investigated in the field of underwater robot; control and navigational algorithms and software architectures. The main design goal of ISiMI AUV is downsizing which will reduce substantially the operating cost compared to other vehicles previously developed in KORDI such as VORAM or DUSAUV. As a result of design and manufacturing process, ISiMI is implemented to be 1.2 m in length, 0.17 m in diameter and weigh 20 kg in air. A series of tank test is conducted to verify the basic functions of ISiMI in the Ocean Engineering Basin of MOERI, which includes manual control with R/F link, auto depth, auto heading control and a final approach control for underwater docking. This paper describes the implementation of ISiMI system and the experimental results to verify the function of ISiMI as a test-bed AUV platform.
Optimum Design of Two-Dimensional Steel Structures Using Genetic Algorithms
Kim, Bong-Ik ; Kwon, Jung-Hyun ;
Journal of Ocean Engineering and Technology, volume 21, issue 2, 2007, Pages 75~80
The design variables for structural systems, in most practical designs, are chosen from a list of discrete values, which are commercially available sizing. This paper presents the application of Genetic Algorithms for determining the optimum design for two-dimensional structures with discrete and pseudocontinuous design variables. Genetic Algorithms are heuristic search algorithms and are effective tools for finding global solutions for discrete optimization. In this paper, Genetic Algorithms are used as the method of Elitism and penalty parameters, in order to improve fitness in the reproduction process. Examples in this paper include: 10 bar planar truss and 1 bay 8-story frame. Truss with discrete and pseudoucontinuous design variables and steel frame with W-sections are used for the design of discrete optimization.
Block Assembly Planning Using Case-based Reasoning and Expert System
Sheen, Dong-Mok ;
Journal of Ocean Engineering and Technology, volume 21, issue 2, 2007, Pages 81~86
This paper presents a computer aided process planning system integrating case-based reasoning and expert system for block assembly in shipbuilding. Expert rules are extracted from the case-base where cases are represented as a set of constraint-satisfaction problems. Rules for the expert system are extracted by generalizing the constraints. In generalizing the constraints, parts are generalized as variables or as part-types. The system was developed with CLIPS, an expert system shell. As more cases are collected, more rules will be extracted and the existing rules will be updated.