• The Journal of Fisheries Business Administration
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• v.40 no.2
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• pp.105-126
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• 2009

This study applies the cointegration theory to analyse the causality of the prices between imported fisheries and domestic fisheries in distribution channel. We've focused on the prices of import, wholesale and retail about the frozen Alaska pollack, hairtail and croaker which take up high portion and are popular among most of the consumers. In process of analysis, the unit root test was adopted to find the stability of time series data prior to the cointegration test. If the time series data was found as stable one in unit root test, we should analyse the VAR model. If unstable, the cointegratioin test was adopeted to find the long-run equilibrium relationship between the data. When the long-run equilibrium relationship was found among the price of the import, wholesale and retail price, the VECM model was adoped. If not, the differenced VAR model was adopted. The main findings of this study could be summarized as follows ; First, according to the result of the analysis on VAR model, time series data of frozen Alaska pollack was found as stable and has causality relationship and close effect was existing among the import, wholesale and retail price. Second, the data of frozen hairtail was found as an unstable one in unit root test and the result of cointegration test showed the long-run equilibrium relationship at lag 1. From the results of VECM model, we could find that the coefficient of error correction is effective, and the sign is negative(-). It means that the existence of adjustment tendency to long-run equilibrium after a short-run deviation. But the short-run causality of the prices were not found except the price of wholesale. Third, according to the results of differenced VAR model, data from frozen croaker did not have the stability and long-run equilibrium. Moreover, it was found that the import price has a weak causality on the retail price. Because of having difficulties in collecting data, the result of this paper could not explain the relationship among the prices of import, wholesale and retail perfectly. However, it more or less contributed to a long-lasted debate on the direction of causality of price-setting in academic research and provided a useful guide for the policy makers in charge of the price-setting of fisheries products as well.

• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.327-328
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• 2014

Modern life is surrounded by all kinds of information and screen, motion graphics in these media everywhere, you can use it to a special performance of the method, the use of the stage, so that the effect is more vivid stage performance. Stage design industry began to diversify the use of Motion graphic, have long been out of the framework of the traditional background, turn into dynamic video space. In this paper analysis of research papers by the dynamic changes in the graphics arena background, style, affect the application of dynamic images. Summed up in the stage of development that can adapt to the requirements of the times, better performance stage effects and express emotion of the stage performances.

• Journal of Power Electronics
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• v.12 no.6
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• pp.982-991
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• 2012

In this study, a new method has been presented for the detection of broken rotor bar (BRB) faults in inverter driven induction motors controlled via Field Oriented Control (FOC). To this end, a FOC controlled induction motor with a BRB fault was modeled using the Matlab/Simulink program. Experiments were carried out using the prepared simulation model at various loads and operating speeds. The motor current and speeds were monitored for healthy, 1, 2 and 3 BRB faults. The Resampling Based Order Tracking Analysis (RB-OTA) method was applied to the monitored signals. The obtained results were compared by using the classic Fast Fourier Transform (FFT) method. When the obtained results were analyzed via the FFT method no information regarding any faults was determined in the run up or run down regions of the motor and the presented method gave very good results. The reliability of the proposed method was validated with experimental results. The main innovative part of this study is that the RB-OTA method was implemented on the induction motor current signal for detecting BRB faults.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.558-565
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• 2017

Accurate prediction of wave-structure interactions is important in the safety and design cost effectiveness of fixed and floating offshore structures exposed to extreme environmental conditions. In this study, regular waves and circular column structure interactions for four circular columns in regular waves are analyzed. To simulate 3D two-phase flow, open source computational fluid dynamics libraries, called OpenFOAM, were used. When the four circular columns are arranged in a square array, the interactions according to the incident slopes of the regular waves are analyzed. The wave run-up in the circular column surface was compared according to the slope of the incident wave. It was confirmed that high amplitude waves are generated between the circular columns due to the interaction between the circular column and the incident wave. It is expected that this analytical result will be used as the basic data of the study on the air gap due to the interaction between the structure and incident wave.

• Journal of Ocean Engineering and Technology
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• v.27 no.3
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• pp.43-52
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• 2013

In the present study, a flow analysis for estimating the wave loads acting on a stationary floating body inside a viscous numerical wave tank was performed using the commercial software FLUENT. The governing equations for the viscous and incompressible fluid motion were the continuity and Navier-Stokes equations, and a piston-type wavemaker was employed to reproduce wave environments. First, the optimal simulation conditions were derived through numerical tests for the wavemaker and wave absorber, and then the wave loads and wave run-up on a vertical truncated cylinder were estimated and compared with the experimental and other numerical results.

• Ocean Systems Engineering
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• v.4 no.3
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• pp.169-183
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• 2014

For the reliable design of substructure supporting offshore wind turbines it is very important to reduce the effects of wave forces. Since the substructure is strongly influenced by the effects of wave forces as the size of substructure increases. In the present study, the hybrid substructure with multi-cylinder is newly suggested to reduce the effects of wave forces. Using diffraction theory the scattering waves in a fluid region are expressed by an Eigenfunction expansion method with three dimensional potential theory to calculate the wave force acting on the hybrid substructure. The wave force and wave run-up acting on the hybrid substructure is presented to examine the water wave interaction according to the variation of cylindrical size and the distance among cylinders. It is found that the suggested hybrid substructure with multi-cylinder is very useful to reduce the effects of wave forces acting on the substructure for offshore wind turbines.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.479-483
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• 2004

A new calculation method of expected overtopping probability of rubble mound breakwater considering real tide occurrence has been proposed. A calculation method of expected overtopping probability of rubble mound breakwater was proposed by Kweon and Suh (2003). In their calculation, the fluctuation of tidal elevation was expressed by the sinusoidal change that yields the uniform distribution of occurrence frequency. However, the realistic distribution of tidal elevation should influence on the overtopping chance. In this study, the occurrence frequency of tidal elevation obtained from the real sea is included. The tidal elevation used in this study is collected from the east coastal part of Korean peninsular. Analyzing the annual data of the tidal fluctuation measured hourly during 355 days, the distribution of occurrence frequency is formulated utilizing by the normal distribution with one peak. Among the calculation procedures of annual maximum wave height, wave height-period joint distribution, wave run-up height and occurrence frequency of tide, only the annual maximum wave height is again chosen randomly from normal distribution to consider the uncertainty. The others are treated by utilizing the distribution function or relationship itself, It is found that the inclusion of the variability of tidal elevation has great influence on the computation of the expected overtopping probability of rubble mound breakwater. The bigger standard deviation of occurrence frequency is, the lower the overtopping probability of rubble mound breakwater is.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.130-138
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• 2002

This paper presents the modeling and analysis of dynamic characteristics of hydraulic snubber in electric power plant. The nonlinear state-space model of 14th order to describe the dynamics of the snubber was established by Simulink. The simulation results show that the hydraulic snubber reacts as like the conventional shock absorbers against the high pulse shock load. The snubber also shows the peculiar characteristics to the small step load, which temporarily lock the control valves up, however maintain same steady-state pressures of all internal chambers in the long run. Two case studies for the analysis of the snubber were addressed. Practical pulse testing method was also proposed to identify the frequency response characteristics of the snubber.

• Journal of computational fluids engineering
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• v.19 no.4
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• pp.52-60
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• 2014

Recently, coastal structures have been built to protect coastal areas. However, if a tidal wave caused by an earthquake hits the coast, it would cause catastrophic damages. It is important to analyze the basics and the characteristics of a tsunami to reduce damages caused by natural disasters. In this study, a tsunami passing over different topographical changes is simulated with VOF method based on FVM(Finite Volume Method). The reduction of both scale and velocity is accomplished by similarity analysis, and an initial energy is generated by increasing the water level as needed to create a tsunami as if it is caused by a crustal movement. It is found that the present method is appropriate to simulate the tsunami with its mechanism.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.3
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• pp.271-278
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• 2023

This study aims to analyze the income structure, cost structure, and profit structure based on data related to the business performance of the boat seine fishery from 1990 to 2020, and to identify the direct and indirect factors affecting fishery profitability through panel regression analysis. The main analysis results are as follows. First, it was found that fish catch has a significant amount of impact on fishery profitability, which is a key factor in improving the profitability of anchovy boat seine fishery. Second, it is necessary to develop carbon-reduced fishing gear, develop fleet-reduced fishing gear, and improve the operating system in order to increase fishery profitability for the short run. Third, it is necessary to create and maintain sustainable profitability for the long run, the continuous fishing vessels buyback program, an active responses to climate change, and the follow-up investigations about marine aggregate extraction in the south sea EEZ are needed.