• Computational Structural Engineering
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• v.9 no.4
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• pp.209-217
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• 1996

An Inverse modal perturbation method was applied to estimate the assessments of the damages at the large-scaled marine structure, such as pier or dolphin, from the structural dynamic natural frequencies and mode shape. Vibrations of structural stiffness, natural frequencies and mode shapes from the eigenvalue analysis lead to the modal peturbation equations, which were considered with a second order term. This paper estimates the assessments of the damages for the structure with the decreased stiffness and shows the convergence of perturbation equation.

• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.115-119
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• 2001

The simulation of motion responses of a dolphin-moored ocean structure in shallow water when it cllides with a ship, has been carried out. The equation of motion in the time domain according to Cummin's theory is employed, and solved by making use of the Newmark-${\beta}$ method. The added mass and damping coefficients involved in the equations are abtained from a three-dimensional panel method in the frequency domain. The impact forces due to ship collision are calculated using both the elastic and non-elastic modelings. The mooring forces for dolphin systems of ocean structure are regarded as linear spring forces.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.237-244
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• 1998

Optimum design of mooring dolphin is numerically investigated. Design optimization problem of mooring dolphin is first formulated. Geometry and cross sections of piles are used as design variables. Design objective is the total weight of steel piles of mooring dolphin and the constraints of stress, penetration depth, lower and upper bounds on design variables are imposed. Based on the design variable linking and fixing, several class of design variations are sought. For the numerical optimization, both PLBA( Pshenichny-Lim-Belegundu-Arora) program and DNCONF subroutine code in IMSL library are used. For a dolphin with 20 steel piles, vertical and inclined, optimum designs for different cases are successfully obtained, which can be applied for the mooring of a large floating structure.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.103-107
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• 2001

When ship claps against the ocean structure sited at shallow water, the time simulation of motion responses of dolphin-moored ocean structure is presented. The equatien of motion based on Cummin's theory of impulse responses are employed, and solved in time domain by using the Newmark $\beta$ method. The added mass and damping coefficients involved in the equations are obtained from a three-dimensional panel method in the frequency domain. The impact forces due to ship collision are modeled as two method, and those are elastic and non-elastic collisions. The mooring forces for dolphin systems of scean structure are considered as linear spring system.

• Explosives and Blasting
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• v.33 no.2
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• pp.25-39
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• 2015

The common underwater rock removal methods involve underwater blasting and crane's chisel dropping impact method. From an environmental point of view, these methods cause ground vibrations and underwater noise. At the site for this study, a method of dropping heavyweight chisel is selected to remove the underwater bedrock near the ferry rack in the course of improving the cargo handling ability of the loading dock. A prediction formula for the vibration was obtained based on the measurement and evaluation of the vibrations caused by the chisel dropping impacts during the test droppings. The prediction formula was successfully applied to the main construction for securing the stability of the structure.

• The Journal of the Convergence on Culture Technology
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• v.2 no.1
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• pp.13-33
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• 2016

In arts, literary is always dealing human emotion and it makes a man weap or laugh among them. Hence, insight on how to write a poet is very effective in view of literary theraphy. The healing effect by literary theraphy on the invisible frame of life gives the resultant limitation using the poetry of a fixed form. Therefore, the search on how to write the free human immune system related on neurons or on how to deal with literary drugs makes our technique creatively developed. In this study, "the right writings for Korean poetry of a fixed form 'Writing Sijo'" is shown to make the literary theraphy more extensible and it is shown to makes the life quality more abundant. This paper suggests the right writing methodology of Sijo in such a view point.

• Journal of Internet Computing and Services
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• v.23 no.4
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• pp.1-9
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• 2022

Recently, the functions of smart speakers have diversified, and the penetration rate of smart speakers is increasing. As it becomes more widespread, various techniques have been proposed to cause anomalous behavior against smart speakers. Dolphin Attack, which causes anomalous behavior against the Voice Controllable System (VCS) during various attacks, is a representative method. With this method, a third party controls VCS using ultrasonic band (f>20kHz) without the user's recognition. However, since the method uses the ultrasonic band, it is necessary to install an ultrasonic speaker or an ultrasonic dedicated device which is capable of outputting an ultrasonic signal. In this paper, a smart speaker is controlled by generating an audio signal modulated at a frequency (18 to 20) which is difficult for a person to hear although it is in the human audible frequency band without installing an additional device, that is, an ultrasonic device. As a result with the method proposed in this paper, while humans could not recognize voice commands even in the audible band, it was possible to control the smart speaker with a probability of 82 to 96%.

• Journal of Navigation and Port Research
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• v.30 no.6 s.112
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• pp.447-455
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• 2006

Together with the trend of enhancement in domestic industrial development and economic progress due to import and export, the demand for construction of the roads, bridges, especially port facilities, and several coastal protection and ocean structures is increasing rapidly. MOMAF of Korean Government is driving construction cf 9 new ports and renovation cf the existing fishery ports. Among these structures most of bridge base, wharves, dolphins, quays, and jetties are being newly built cf steel or concrete pile. As the base, supporting bulkheads, and piles are underwater after construction, it is difficult to figure out the status of structures and not enough to get maintenance and strengthen the structures. Every year, moreover, these works suck the government budget due to higher incomplete maintenance expense for protection from corrosions cf structures and increased underwater construction period. For the purpose cf cutting down the expense cf government budget, it is necessary to extend the life cycle of the existing structures. Therefore, we developed a new method for maintenance of submerged structures near the waterline by allowing dry work environment with the floating caisson. The method shows easy to move around the working area and handle. It also showed not only a significant reduction of maintenance expenses and time for anti-corrosion work but also better protection This will be a milestone to reduce the maintenance and construction expenses for the shore and water structures.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.3
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• pp.211-217
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• 2008

Natural environment, topographical conditions and marine traffic flows were investigated and questionnaire surveys were performed for the purpose of understanding the cause of marine accidents. The frequent cases of ships' dragging have happened at the anchorages of E-1, E-2 and E-3. The anchorage area is insufficient for the accommodation of a number of ships, the dolphins at the nearby piers are located near a narrow fairway. SBMs' are positioned too close to the fairway. It shows that many crossing marine traffic flows occur in all areas of the port. Marine casualties are concentrated mainly at No. 1 fairway, M1-M7 waters close to the dolphins and Gwanjeolgot, "E" anchorage and the waters close to the fairway "come and go" areas. The marine traffic flow is mainly caused by the ships' movement at the inter-port and most of the ships are the dangerous cargo carriers. And small ships like the tug-barge are moving disorderly in the ports. Furthermore, the fairway‘s layout is crossing each other. Questionnaire surveys of the users and experts shows that the LANBY that can distinguish the fairway of "come and go" ports is required.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.163-170
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• 2006

Together with the trend of enhancement in domestic industrial development and economic progress due to import and export, the demand for construction of the roads, bridges, especially port facilities, and several coastal protection and ocean structures is increasing rapidly. MOMAF of Korean Government is driving construction of 9 new ports and renovation of the existing fishery ports. Among these structures most of bridge base, wharves, dolphins, quays, and jetties are being newly built of steel or concrete pile. As the base, supporting bulkheads, and piles are underwater after construction, it is difficult to figure out the status of structures and not enough to get maintenance and strengthen the structures. Every year, moreover, these works suck the government budget due to higher incomplete maintenance expense for protection from corrosions of structures and increased underwater construction period. For the purpose of cutting down the expense of government budget, it is necessary to extend the life cycle of the existing structures. Therefore, we developed a new method for maintenance of submerged structures near the waterline by allowing dry work environment with the floating caisson. The method shows easy to move around the working area and handle. It also showed not only a significant reduction maintenance expenses and time for anti-corrosion work but also better protection. This will be a milestone to reduce the maintenance and construction expenses for the shore and water structures.