• Journal of Navigation and Port Research
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• 제46권5호
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• pp.449-457
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• 2022

The Port of Busan is currently ranked as the seventh largest container port worldwide in terms of cargo throughput. However, port competition in the Far-East region is fierce. The growth rate of container throughput handled by the port of Busan has recently slowed down. In this study, we analyzed how economic conditions and multiple external shocks could influence cargo throughput and identified potential implications for port business. The aim of this study was to build a model to accurately forecast port throughput using the ARIMA model, which could incorporate external socio-economic shocks, and the VEC model considering causal variables having long-term effects on transshipment cargo. Findings of this study suggest that there are three main areas affecting container throughput in the port of Busan, namely the Russia-Ukraine war, the increased competition for transshipment cargo of Chinese ports, and the weaker growth rate of the Korean economy. Based on the forecast, in order for the Port of the Port of Busan to continue to grow as a logistics hub in Northeast-Asia, policy intervention is necessary to diversify the demand for transshipment cargo and maximize benefits of planned infrastructural investments.

• Journal of Ocean Engineering and Technology
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• 제38권2호
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• pp.53-63
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• 2024

Submerged breakwaters can be installed underneath floating structures to reduce the external wave loads acting on the structure. The objective of this study was to establish an optimization analysis framework to determine the corresponding shape and position of the submerged breakwater that can minimize or maximize the external forces acting on the floating structure. A two-dimensional frequency-domain boundary element method (FD-BEM) based on the linear potential theory was developed to perform the hydrodynamic analysis. A metaheuristic algorithm, the advanced particle swarm optimization, was newly coupled to the FD-BEM to perform the optimization analysis. The optimization analysis process was performed by calling FD-BEM for each generation, performing a numerical analysis of the design variables of each particle, and updating the design variables using the collected results. The results of the optimization analysis showed that the height of the submerged breakwater has a significant effect on the surface piercing body and that there is a specific area and position with an optimal value. In this study, the optimal values of the shape and position of a single submerged breakwater were determined and analyzed so that the external force acting on a surface piercing body was minimum or maximum.

• Journal of Biomedical Engineering Research
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• 제24권4호
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• pp.347-354
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• 2003

In this paper, a computational method of an action potential including the effect of extremely low frequency and mobile phone (external) electromagnetic fields is Proposed. The method is based on the Hodgkin and Huxley model, applies the effect of the electromagnetic fields on the action Potential in terms of a binding factor into the injection current of the model, and calculates the Strength-Duration curve from numerical experiments for a frequency range of electromagnetic fields. In the numerical experiments, the coupled ordinary differential equations of the action potential and the state variables are solved solf-consistently by using Runge-Kutta Fehlberg method. The range of the frequency considered is from 1Hz through 100Hz and of 900MHz, which is specific for a mobile Phone. The Strength-Duration curves resulted showed good agreements with the equation suggested by Hodgkin and Huxley.

• The Journal of Information Systems
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• 제32권3호
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• pp.225-251
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• 2023

Purpose The purpose of this study is to examine the future direction of in-vehicle app development and service, the relationship between potential customers' intention to use and the factors that affect it was explored. It was also checked whether the two types of app development platform and the experience of the existing smartphone app platform had a moderating effect on these relationships. Design/methodology/approach Data was gathered through surveys, collecting responses from 904 potential consumers of vehicle app services in Korea. Structural equation modeling was utilized to analyze the data. Findings According to the empirical analysis result, it was found that potential customers considered enjoyment as the most important benefit factor in in-vehicle app service, and the most important external factor affecting enjoyment was functional compatibility with smartphone. The type of vehicle app development platform did not have a meaningful moderating effect on the factor relationship, whereas the smartphone app platform experience showed a meaningful moderating effect on the relationship between factors. It was analyzed that the risk of app performance, personal information privacy, and driving safety data did not have a negative effect on the intention to use the vehicle app service.

• Proceedings of the KSME Conference
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3473-3478
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• 2007

A dual side cooling annular fuel having internal and external coolant channels has many advantages basically due to low fuel temperature and high DNBR margin, which can make a significant increase of core power density possible. So recently a 12x12 square annular fuel array was proposed for the fuel assembly to be reloaded without structural interference with operating reactors of OPR-1000s. Even through the inherent potential of the annular fuel on the high power density, it may be seriously eroded in the case of a severe unbalanced mass flux split to the internal and external channels in standpoint of DNB. Mass flux split is determined pressure drop characteristics between inner and outer channels. The spacer grids binding fuel array influence greatly the pressure drop in outer channels and the mass flux split. As an important factor of DNB behavior, the enthalpy differences at both channel exits were evaluated using the mass flux splits.

• Structural Engineering and Mechanics
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• 제66권5호
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• pp.595-608
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• 2018

This paper deals with the lateral - torsional motion of bridges provided with external cables acting as dampers under the action of horizontal dynamic loads or of walking human crowd loads. A three dimensional analysis is performed for the solution of the bridge models. The theoretical formulation is based on a continuum approach, which has been widely used in the literature to analyze bridges. The resulting equations of the uncoupled motion are solved using the Laplace Transformation, while the case of the coupled motion is solved through the use of the potential energy. Finally, characteristic examples are presented and useful results are obtained.

• Interaction and multiscale mechanics
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• 제2권2호
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• pp.209-222
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• 2009

This article describes recent work on mechanics of carbon nanotubes, one of the most fundamental and amazing man-made nanostructures. The noteworthy point is that "nano"-scale mechanics of carbon nanotubes can be well described by the continuum elastic theories for "macro"-scale thin shells. This provides an efficient means to elucidate mechanical deformation effects of carbon nanotubes on their physical and chemical properties, which is significant to develop new-generation nanomaterials based on nanotubes and their composites. Potential applications of the mechanical deformation of nanotubes in nano-electronics and nano-biology are also commented. In addition, theoretical investigations regarding external pressure buckling is carried out here and we have numerically confirmed that larger N (the number of layers) and a smaller D (the innermost diameter) make "corrugation modes" with a larger mode-index k be energetically favored.

• Ceramist
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• 제23권1호
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• pp.27-37
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• 2020

Recently, 4D printing technology has received considerable attention in various industries and research fields including soft robotics, tissue engineering, electronics. In 4D printing process, 3D printed object transforms itself into programmed structure by the input of external energy. Thus, this process requires not only smart materials, capable of changing their properties or features in response to external stimuli such as electricity, temperature, light, etc., but also smart structures, multi-material 3D printing, simulation and so on. In this review, the concept, technical elements and potential of 4d printing are presented.

• English Language & Literature Teaching
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• 제10권3호
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• pp.67-88
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• 2004

Given the noteworthy increase in the number of native-born English-speaking. EFL instructors teaching overseas, this research examined 6 American EFL instructors who had taught English abroad with special reference to their experience as foreigner instructors in their respective host countries. With the use of interviews as the major technique employed, this research was centered on identifying conflicts or difficulties the research participants encountered as novice instructors, both internal and external to the classroom settings of their host countries. Research findings revealed that the current participants were not adequately prepared to cope with new and unfamiliar physical settings of their host countries, or to familiarize themselves with their new classroom settings and students. Studying the various the conflicts which native EFL instructors encountered, both internal and external to the classroom environment, will hopefully shed light on, and provide a more accurate portrayal of EFL professionals' teaching overseas and may provide possible insights into potential solutions to them. Furthermore, the research findings were considered and discussed in terms of acculturation theory.

• Journal of Welding and Joining
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• 제32권3호
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• pp.53-59
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• 2014

The mechanical stability of solder joints in electronic devices with Sn-Ag-Cu is a continuous issue since the material was applied to the industry. Various shock test methods were developed and standardized tests are used in the industry worldwide. Although it is applied for several years, the detailed mechanism of the shock induced failure mechanism is still under investigation. In this study, the effect of external temperature was observed on large Flip-chip BGA components. The weight and size of the large package produced a high strain region near the corner of the component and thus show full fracture at around 200G level shock input. The shock performance at elevated temperature, at $100^{\circ}C$ showed degradation based on board pad designs. The failure mode and potential failure mechanisms are discussed.