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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Society of Coastal and Ocean Engineers
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Korean Society of Coastal and Ocean Engineers
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Volume & Issues
Volume 22, Issue 6 - Dec 2010
Volume 22, Issue 5 - Oct 2010
Volume 22, Issue 4 - Aug 2010
Volume 22, Issue 3 - Jun 2010
Volume 22, Issue 2 - Apr 2010
Volume 22, Issue 1 - Feb 2010
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Control of Short-period and Solitary Waves Using Two-rowed Impermeable Rectangular Submerged Dike
Lee, Kwang-Ho ; Jung, Sung-Ho ; Ha, Sun-Wook ; Kim, Do-Sam ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 22, issue 4, 2010, Pages 203~214
This study numerically investigates the wave control of 2-rowed Impermeable Rectangular Submerged Dike(IRSD) with an object of how to control short-period and solitary waves simultaneously based on the Bragg resonance phenomenon that elevates the wave control performance. The boundary integral method using Green formula and the 3-D one-field Model for immiscible TWO-Phase flows (TWOPM-3D) by 3-D numerical wave flume have been used for the numerical predictions for short-period and solitary waves, respectively. These numerical models were verified through the comparisons with the previously published numerical results by other researchers. Through the parametric tests of numerical experiments for short-period waves, an optimum model of 2-rowed IRSD of a lowest transmission coefficient has been found. Furthermore, the performances of 3-D wave control for solitary waves were evaluated for the various free board, crown widths and gap distance between dikes, and have been compared with those of a single-rowed IRSD. Numerical results show that a 2-rowed IRSD with a less cross sectional area than 1-rowed one improves the wave attenuation performances when it is compared to that of single-rowed IRSD. Within the test frequency ranges of the numerical simulations conducted in this study, 2-rowed IRSD with an optimum gap distance shows an outstanding improvement of the wave attenuation up to 58% compared to that of single-rowed IRSD.
Water Circulation Structure in the Chinju Bay of Korea
Kim, Cha-Kyum ; Lee, Jong-Tae ; Jang, Ho-Sik ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 22, issue 4, 2010, Pages 215~223
A seasonal circulation patterns in the Chinju Bay (CB) were suggested from the observed data at two channels of the Noryang Channel (NC) and the Daebang Channel (DC) during the period from 2005 to 2008. The water circulation in the CB is mainly controlled through the NC and the DC. In winter, tidal current at the surface layer of the NC flows from the Kwangyang Bay (KB) eastward into the CB, whereas the current at the bottom layer flows from the CB westward into the KB. In summer, tidal current at the surface layer of the NC goes from the CB westward into the KB. The flow system at the NC shows the typical pattern of thermohaline circulation. In spring, tidal current at the surface layer of the eastern part of the DC flows out into southeastern open ocean. However, in summer, the current in the western part of the DC flows into the CB through the DC. Also, the velocity in the western part of DC is 50~70 cm/sec stronger than that in the eastern part. To obtain better understanding on the seasonal circulation pattern in the NC and the DC, additionally the detailed studies on the field measurements and three dimensional numerical modeling are needed.
Collision Fragility Analysis of Offshore Bridge by Ship
Cho, Byung-Il ; Kim, Dong-Hyawn ; Oh, Young-Min ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 22, issue 4, 2010, Pages 224~229
Collision fragility analysis of offshore bridge by ship was performed. Collision velocity and angle were chosen as random variables then collision of 18,000DWT and 30,000DWT ships with bridge was analyzed. Displacement response surface of bridge by ship collision was estimated by varying ship velocity from 2 m/s to 7 m/s. Using the result of reliability analysis, fragility curves of collision was established and risk of offshore bridge to collision velocity as median and log-standard deviation was presented.
The Effect of Wall Friction on Deformation Characteristics of the Cellular Bulkhead
Son, Dae-San ; Jang, Jeong-Wook ; Kim, Kyong-Yeol ; Kim, Hyun-Guk ; Chung, Youn-In ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 22, issue 4, 2010, Pages 230~234
This study examined the effect of wall friction on deformation characteristics of the cellular bulkhead, in terms of artificial wall friction based on the results of model tests according to the existing penetration ratio and loading height. 1. The effect of wall friction on deformation characteristics of the cellular bulkhead turned out to be less as the loading height decreases and the penetration ratio increases. The yield load also becomes less as wall friction decreases. 2. The ratio of the rotational displacement to the horizontal displacement of the cellular bulkhead becomes less as the loading height decreases and the penetration ratio increases. Hence it is concluded that the effect of wall friction has close relationship with the rotational displacement.
Reduction of the Foam Generated in the Discharge Channel of a Power Plant
Oh, Young-Min ; Oh, Sang-Ho ; Jang, Se-Chul ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 22, issue 4, 2010, Pages 235~240
The foam produced by the effluent cooling water which is released to the discharge channel provokes civil complaints due to the visual pollution to the neighboring residents. In this study, a physical model test was conducted by placing tetrapods on the bottom slope of the discharge channel in order to suggest an effective method of reducing the amount of generated foam. Field application of the main results of the model test showed qualitatively apparent reduction of the foam generation at the discharge channel.
Application of Macrocell Sensor System for Monitoring of Steel Corrosion in Concrete Structure Exposed to Marine Environment
Lee, Seung-Tae ; Moon, Dae-Joong ; Kim, Wan-Jong ; Moon, Jae-Heum ; Kim, Hak-Soo ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 22, issue 4, 2010, Pages 241~247
Corrosion of steel embedded in concrete is one of the foremost factors that affect the durability of concrete structures in marine environments. This paper presents an application technique of anode-ladder-system to evaluate corrosion behaviours of marine concrete structure. In order to investigate the behaviours quantitatively, the measurement of potential and current was performed on the concrete elements subjected to the penetration and diffusion of chloride ions. The main variable was the heights from seawater level; namely 3.7, 6.0 and 8.2 m. As a result of the monitoring, it was found that the corrosion characteristics differently behaved with the increasing height. Additionally, through migration test, the relationship between compressive strength of concrete and diffusivity of chloride ions was observed. It is suggested, ultimately, that in order to reduce or mitigate steel corrosion, both appropriate concrete cover depth and high-quality of concrete in early ages should be done.
Applicability of Coupled Tide-Surge Model
Park, Seon-Jung ; Kang, Ju-Whan ; Kim, Yang-Seon ; Moon, Seung-Rok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 22, issue 4, 2010, Pages 248~257
Applicability of the MIKE21 model as a real time coupled tide-surge model is examined prior to the application as an inundation model. Though the model domain contains the whole southern coasts of Korean Peninsula, the results of tide simulations show good agreement with the observed values. Moreover, the coupled tide-surge model simulates water levels well, especially near the sites which typhoon MAEMI(0314) struck, such as at Tongyung, Masan and Pusan. In addition, it is confirmed that the interaction between storm surge and tide is notable where the water depth is small and the tidal range is large, which indicates the necessity of coupled model especially at the southwestern coast.
Simulation of Water Quality Changes in the Saemangeum Reservoir Induced by Dike Completion
Suh, Seung-Won ; Lee, Hwa-Young ; Yoo, Sang-Cheol ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 22, issue 4, 2010, Pages 258~271
In order to figure out hydrodynamic and water quality changes after completion of dike construction of the Saemangeum, which behaves as a semi-enclosed estuarine lake, numerical simulations based on fine grid structure by using EFDC were intensively carried out. In this study some limitations of precedent study has been improved and gate operation were considered. Also 3 phases such as air-water-sediment interaction modeling was considered. It is clear that inner mixing of the Saemangeum is dominated by Mankyeong and Dongjin riverine discharges rather than the gate opening influence through the Lagrangian particle tracking simulations. Vertical DO structure after the dike completion shows steep gradient especially at Dongjin river estuary due to lessen of outer sea water exchange. Increasing SOD at stagnantly changed man-made reservoir might cause oxygen deficiency and accelerating degradation of water quality. According to TSI evaluation test representing eutrophication status, it shows high possibility of eutrophication along Mankyeong waterway in spite of dike completion, while the index is getting high after final closing along Dongjin waterway. Numerical tests with gate operations show significant differences in water quality. Thus it should be noted that proper gate operation plays a major role in preserving target water quality and management for inner development plan.
Microscopic Influence of Temperature on Carbonation for Marine Concrete Structure
Han, Sang-Hun ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 22, issue 4, 2010, Pages 272~278
Some recent researches reported that high temperature rising decreases the carbonation depth of concrete, which is contrary to the previous research results. Carbonation has been known as a reaction between calcium hydroxide and carbon dioxide. But a few researches showed that the other cement hydrates as well as calcium hydroxide react with carbon dioxide. This paper investigates the influence of temperature on carbonation and the variation of
by carbonation. In order to estimate the carbonation depth and the quantities of reactant and product of carbonation reaction, phenolphthalein testing and thermagravimetric analyzer test were conducted. The measurement of carbonation depth with temperature showed that the temperature increase from
C in carbonation environment makes the carbonation depth larger, but the increase from
has a small influence on the carbonation depth. Comparing calcium hydroxide and calcium carbonate with temperature, the quantity of
of specimen carbonated at
is greater than that of specimen carbonated at
and the quantity of
of specimen carbonated at
is similar to that of specimen carbonated at
. This observation shows that there is the optimum temperature increasing carbonation depth and the optimum temperature is close to
Analysis of the Mean and Standard Deviation due to the Change of the Probability Density Function on Tidal Elevation Data
Cho, Hong-Yeon ; Jeong, Shin-Taek ; Lee, Khil-Ha ; Kim, Tae-Heon ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 22, issue 4, 2010, Pages 279~285
In the process of the probabilistic-based design on the coastal structures, the probability density function (pdf) of tidal elevation data is assumed as the normal distribution function. The pdf shape of tidal elevation data, however, is better-fitted to the double-peak normal distribution function and the equivalent mean and standard deviation (SD) estimation process based on the equivalent normal distribution is required. The equivalent mean and SD (equivalent parameters) are different with the mean and SD (normal parameters) estimated in the condition that the pdf of tidal elevation is normal distribution. In this study, the difference, i.e., estimation error, between equivalent parameters and normal parameters is compared and analysed. The difference is increased as the tidal elevation and its range are increased. The mean and SD differences in the condition of the tidal elevation is
are above 100 cm and about 80~100 cm, respectively, in Incheon station. Whereas, the mean and SD differences in the condition of the tidal elevation is
are very small values in the range of 2~4 cm, in Pohang station.