• Journal of Navigation and Port Research
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• v.36 no.5
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• pp.339-347
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• 2012

After towing rope connecting a barge to a tug was subdivided into multiple finite elements, then those dynamic models was established using Newton's second law and considering the external force and moment such as tension, drag, Coriolis force, gravity, buoyancy, and impact due to free surface acting on each element. While the previous research on the model of towing rope considered only translation, five-degree-of-freedom equations of motion except roll based on the body-fixed frame were established in this paper. All elements are connected by a spring and a damper, and the stiffness of the spring was set as the equivalent value of the real rope. In order to confirm the established multiple finite element model, various scenarios such as freely falling of towing rope in the air and above the free surface, accelerating of a tug which tows a barge connected by towing rope, and sinusoidal moving of a tug were set up and simulated. As the results, the trajectories of the tug, the barge, and the towing rope showed good tendencies to the ones of real expected situations.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.1
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• pp.49-61
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• 2007

Otter boards in the trawl are the one of essential equipments for the net mouth to be spread to the horizontal direction. Its performance should be considered in the light of the spreading force to the drag and the stability of towing in the water. Up to the present, studies of the otter boards have focused mainly on the drag and lift force, but not on the stability of otter boards movement in 3 dimensional space. In this study, the otter board is regarded as a rigid body, which has six degrees of freedom motion in three dimensional coordinate system. The forces acting on the otter boards are the underwater weight, the resistance of drag and spread forces and the tension on the warps and otter pendants. The equations of forces were derived and substituted into the governing equations of 6 degrees of freedom motion, then the second order of differential equations to the otter boards were established. For the stable numerical integration of this system, Backward Euler one of implicit methods was used. From the results of the numerical calculation, graphic simulation was carried out. The simulations were conducted for 3 types of otter boards having same area with different aspect ratio(${\lambda}=0.5,\;1.0,\;1.5$). The tested gear was mid-water trawl and the towing speed was 4k't. The length of warp was 350m and all conditions were same to each otter board. The results of this study are like this; First, the otter boards of ${\lambda}=1.0$ showed the longest spread distance, and the ${\lambda}=0.5$ showed the shorted spread distance. Second, the otter boards of ${\lambda}=1.0$ and 1.5 showed the upright at the towing speed of 4k't, but the one of ${\lambda}=0.5$ heeled outside. Third, the yawing angles of three otter boards were similar after 100 seconds with the small oscillation. Fourth, it was revealed that the net height and width are affected by the characteristics of otter boards such as the lift coefficient.

• Journal of the Korea Fashion and Costume Design Association
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• v.23 no.1
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• pp.37-45
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• 2021

This study observed the release of microplastics according to washing weights and filtering conditions, measured microplastic generation rates, fiber lengths, and fiber diameters. This study attempted to present data for the development of filters that decrease microplastic generation. For test samples, polyester piled knit fabric (cut-pile) was selected, which currently has the highest amount of consumption in the clothing industry, but can easily cause marine pollution because of its low biodegradability. For test equipment, a drum washer was used and microplastics were collected using two filter pore sizes, 5 ㎛ and 20-25 ㎛. Microplastic fibers weights and lengths were measured. The results of the experiment showed the following: 1) The release of microplastics differed according to the fabric weights and washing process; 2) washing fabric weights showed a differences in the collection amount according to the filter pore size (5 ㎛, 20-25 ㎛); 3) observations of differences in the lengths of the microplastics that occur during the washing process by filter pore size were made. Fibers with shorter lengths appeared with filter pore sizes of 5㎛ in comparison to filter pore sizes of 20-25㎛. The results from this study on microplastic generation by fabric during washing, demonstrated the following conclusions that can be used to reduce the release of microplastics. First, the release of microplastics according to fabric weights and washing courses are affected by physical force. Therefore, it is necessary to reduce the amount of physical force due to water flow, increase the fabric weight, or wash the material in low temperatures. Second, in the manufacturing of washing machines, microplastic filtration can be promoted or legislatation supporting microplastic filtration can be introduced.

• Food Science of Animal Resources
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• v.26 no.1
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• pp.64-69
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• 2006

This study was conducted to determine the effect of pH adjustment on physico-chemical characteristics of chicken breast surimi. The chicken breast meat was ground with distilled water, of which pH was then adjusted to 2.5 (T1), 3.0 (T2), 10.5 (T3) and 11.0 (T4) for surimi manufacture, respectively. Water content was higher in order of T4>T1>T3>T2 (p<0.05). Crude protein and crude fat were higher in T3 and T4 compared with T1 and T2 (p<0.05). $L^*$ values, myofibrillar protein and water holding capacity of T2 and T4 were higher than those of T1 and T3 (p<0.05). T4 had the lowest yield among the treatments (p<0.05). T1 was higher in yield and pH, whereas breaking force and deformation were higher in T1 (p<0.05). $a^*$ was higher in order of T3>T2>T4>T1 and $b^*$ was lower in T1 compared with other treatments (p<0.05). In textural properties, the chewiness values of T2 and T3 were higher than those of T1 and T4, the hardness was higher in order of T2>T3>T4>T1 (p<0.05). Cohesiveness and gumminess of T1 showed higher values than those of other treatments (p<0.05). In sensory evaluation, the note for appearance was higher in T2 than other treatments (p<0.05), however other traits were not significantly different (p>0.05). Therefore, the alkaline processing (T4, pH 11.0) would be recommended.

• Journal of Life Science
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• v.17 no.5 s.85
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• pp.728-734
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• 2007

In this study, we prepared surimi from pork leg and chicken breast by pH adjustments of 3.0 and 11.0. The content of crude protein, yield, water-holding capacity, redness, yellowness, myoglobin(Mb) and metmyoglobin(metMb) were significantly higher in the surimi manufactured from pork leg at adjustment pH 3.0 compared to the other surimi samples; whereas whiteness, myofibrillar protein, breaking force, deformation and gel strength were lower than other samples(P<0.05). The textural attributes were significantly higher in the surimi manufactured from pork leg at adjustment pH 11.0 compared to the other surimi samples; whereas Mb, metMb, cooking loss, breaking force, deformation and gel strength were lower than other samples(P<0.05). Again, the content of crude protein, yield, pH, breaking force, deformation, gel strength and lightness were significantly higher in the surimi manufactured from chicken breast at adjustment pH 3.0 compared to the other surimi samples; whereas myofibrillar protein, redness and metMb were higher than other samples(P<0.05). The content of myofibrillar protein, deformation, lightness and cohesiveness were significantly higher in the suriml manufactured from chicken breast at adjustment pH 11.0 compared to the other surimi samples; whereas Mb, cooking loss, yield and breaking force were higher than other samples(P<0.05). The chicken breast surimi had superior color and gel characteristics than manufactured from pork leg, and adjustment pH 11.0 had superior whiteness and cohesiveness than the pH 3.0 adjusted sample, however, there were no significant differences in sensory attributes among the surimi samples.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.3
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• pp.183-191
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• 2002

In general, the salient features of the floating breakwater have excellent regulation of sea-water keeping the marine always clean, up and down free movement with the incoming and outgoing tides, capable of being installed without considering the geological condition of sea-bed at any water depth. This study discusses the three dimensional wave transformation of the floating breakwater moored by piers, and its dynamic response numerically. Numerical method is based on the boundary integral method and eigenfunction expansion method. It is known that pier mooring system has higher absorption of wave energy than the chain mooring system. Pier mooring system permit only vertical motion (heaving motion) of floating breakwater, other motions restricted. It is assumed in the present study that a resistant force as friction between piers and floating pontoon is not applied far the vertical motion of the floating breakwater. According to the numerical results, draft and width of the floating breakwater affect on the wave transformations greatly, and incident wave of long period is well transmitted to the rear of the floating breakwater, And the vertical motion come to be large for the short wave period.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.1
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• pp.50-60
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• 2015

This paper conducted research on identifying the process of change in fishing gear and organizing the function of periodically-used fishing gear types through net plan and computer simulation by selecting the design of the four types of fishing gear used for the Korea tuna purse seiner in the Western and Central Pacific Ocean, which 1,000 G/T class and whose length over all 60 m class. In the late 1980s, the length of the tuna purse gear was 1,939 m and the design depth was 160 m, but currently, the length and the design depth are 2,515 m and 230 m, respectively. As a result of the simulation, the expansion of the fishing gear increased buoyance, sinking force, sinking depth, surrounded area, and purse wire continuously. Recently, the maximum tension of the currently used purse wire of tuna purse seiner is 23.5 tons and is close to 25.4 tons which is the maximum lift capacity of WS454 winch. The way to improve fishing gear should be proceeded to increase sinking speed rather than expand the size of fishing gear.

• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.5-16
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• 2015

In the long span bridge construction, construction cost portion of large scale marine foundation is about 40% (KICTEP, 2007). In this study, designs for deep water depth large composite foundation of a super long span cable-stayed girder bridge of prototype were performed by three design methods (ASD, LRFD, Eurocode) and the behaviors of a large diameter drilled shaft were analyzed and the 3D numerical analysis was performed. As a result, the soft rock socket lengths in allowable stress design estimation method were the longest. The soft rock socket lengths estimated by the design approach 2 among Eurocode and the LRFD were similar. The longer the socket length socketed in the soft rock was, the smaller the axial force acting on a large-diameter drilled shaft head was and the smaller the settlement of drilled shaft was.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.173-182
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• 2011

The purpose of this paper is to provide useful information for fishermen in the manner of investigation a sinking speed of current type tuna longline gear at the North Pacific Ocean as a new developed tuna longline fishing ground. The sinking depth of mainline in connection with different basket was investigated. The experiments were also performed with different materials such as Supermansen (i.e., PE) and Hitech (i.e., PA) for the mainline to investigate the sinking depth of mainline and hooks. Furthermore, the relation between the sinking depth of hooks and catches are investigated also. The sinking depth of mainline at the first and the last shooting basket shows deeper than that of middle part of a basket due to reduced shortening ratio. The sinking depth of mainline and hook with Hitech material shows more shallow than that of Supermanse material, even the Hitech case was designed to sink deeper than that of Supermanse case. The highest catches arise at the middle part basket as the hook number 7 with around 248m sinking depth. From the results, longline with Hitech material is needed to increase the sinking force for reaching the relevant sinking depth. Moreover, the current strength at the North Pacific Ocean will be considered for further commercial fishing.

• Journal of Power System Engineering
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• v.15 no.1
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• pp.24-31
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• 2011

Rectangular box type structures are used in many fields of civil, mechanical and marine engineering. Especially, Most ship structures are often in contact with inner or outer fluid, like ballast, fuel and stem tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine and propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tanks. Many authors have studied vibration of rectangular tanks containing fluid. Few research on dynamic interaction among tank walls filled with fluid are reported in the vibration of rectangular tanks recently. In case of rectangular tanks, structural coupling between adjacent panels and effect of vibration modes of multiple panels on added mass of water have to be considered. In the previous report, a numerical analysis is performed for the coupling effect between panels of a tank on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region, and mode characteristics in accordance with changing breadth of the plates by using finite element method for plates and boundary element method for fluid region. In this paper, the coupling effect between panels of a tank on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region, and mode characteristics in accordance with changing length, thickness, and boundary condition of the plates are investigated numerically and discussed.