• Journal of Ecology and Environment
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• v.31 no.2
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• pp.89-95
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• 2008

Sensing the approach of a predator is critical to the survival of prey, especially when the prey has no choice but to escape at a precisely timed moment. Escape behavior has been approached from both proximate and ultimate perspectives. On the proximate level, empirical research about electrophysiological mechanisms for detecting predators has focused on vision, an important modality that helps prey to sense approaching danger. Studies of looming-sensitive neurons in locusts are a good example of how the selective sensitivity of nervous systems towards specific targets, especially approaching objects, has been understood and realistically modeled in software and robotic systems. On the ultimate level, general optimality models have provided an evolutionary framework by considering costs and benefits of visually elicited escape responses. A recent paper showed how neural network models can be used to understand the evolution of visually mediated antipredatory behaviors. We discuss this new trend towards integration of these relatively disparate approaches, the proximate and the ultimate perspectives, for understanding of the evolution of behavior of predators and prey. Focusing on one of the best-studied escape pathway models, the Orthopteran LGMD/DCMD pathway, we discuss how ultimate-level optimality modeling can be integrated with proximate-level studies of escape behaviors in animals.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.3
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• pp.143-151
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• 2004

High-speed permanent magnet machines are likely to be a key technology for electric drives and motion control systems for many applications, since they are conductive to high efficiency, high power density, small size and low weight. In high-speed machines, the permanent magnets are often contained within a retaining sleeve. However, the sleeve and the magnets are exposed to high order flux harmonics, which cause parasitic eddy current losses. Rotor losses of high-speed machines are of great importance especially in high-speed applications, because losses heat the rotor, which is often very compact construction and thereby difficult to cool. This causes a danger of demagnetization of the NdFeB permanent magnets. Therefore, special attention should be paid to the prediction of the rotor losses. This paper is concerned with the rotor losses in permanent magnet high-speed machines that are caused by permeance variation due to stator slotting. First, the flux harmonics are determined by double Fourier analysis of the normal flux density data over the rotor surface. And then, the rectilinear model was used to calculate rotor losses in permanent magnet machines. Finally, Poynting vector have been used to investigate the rotor eddy current losses of high-speed Permanent magnet machine.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.2
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• pp.144-148
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• 2004

Generally a ship in a port or canal is guided by tugboat(s), while the ship engine(s) and steering mechanism idle. The shortcomings of this method are insufficient in course keeping ability, danger of collision with waterside structures, time-consuming preparation for tugging, as well as the need to maintain tugboats. A new technology for ship guiding, based on the physical principle of interaction of a solid body with aerated liquids has been developed [1]. Model tests were carried out for the verification of system at slow speed by engine operating conditions and with an idle steering. The developed device has been proved to keep the ship on course safely.

• Journal of Korea Multimedia Society
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• v.19 no.12
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• pp.1970-1980
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• 2016

The problem of food deficiency is a major discouragement to many low-income developing countries. Most of these countries experience constant danger of hunger, malnutrition and diseases as they are unable to maintain their food supplies mainly due to lack of arable lands and modern crop, livestock and fishery production technologies. In addition, the pollutants resulting from the secondary industries are becoming another serious issue in their food problems. The pollutants mixed in the sands blowing from the mainland China and the toxic waters flowing in the farm land form the industrialized zones are some of the examples. The Vertical Farm, or Plant Factory, proposed in this study could be the best alternative food production system for them. Vertical farm is an efficient food production system that yields relatively a large volume of food materials without environmental risks. The system does not require a large open space and manpower and can minimize the possibility of infiltration of pollutants. This research describes a basic model of the system focusing on determining the optimal sites for it based on the meteorological data concentrating on the atmospheric pollutants. The types and volume of pollutants are analyzed and identified through the big data obtained, followed by visualization of analysis results and their comparisons for better understanding.

• Journal of Distribution Science
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• v.14 no.8
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• pp.35-44
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• 2016

Purpose - This study aims to understand the relationship between Chinese local SNS usage and social capital building through Chinese international students in South Korea. A research model that illustrates the relationship between the SNS usage (i.e., intensity, communication and social capital building is proposed. Based on the analysis, this study will provide responses to the question of if SNS really presents the danger of trapping international consumers in their local comfort zone or enhance social capital for the users. Research design, data, and methodology - The survey questionnaire is circulated among the WeChat (a Chinese local SNS) users who are the Chinese international students studying in South Korea. The collected data is analyzed by structural equation method using SPSS and AMOS. Results - Proposed hypotheses of the positive relationships between the attachment of SNS use and both individuals' bridging and bonding social capital are supported. It's also supported that (1) interpersonal communication, (2) interpersonal communication with old friends, and (3) interpersonal communication for making new friends on SNS positively influence individuals' bridging social capital. Conclusions - This paper demonstrates the importance of intensity of WeChat use and interpersonal communication that impact Chinese international students' bridging and bonding social capital on WeChat.

• KIEAE Journal
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• v.8 no.3
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• pp.51-59
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• 2008

response to the global city. It was developed to cope with the decline of the manufacturing industry, a rise in unemployment and a welfare state system in danger. In cities of the concept, there has been much change in existing urban space and accordingly wisdoms and knowledge has been accumulated. The purpose of this research is to scrutinize urban spatial modification of a regenerated model city "Bologna". The target area of analysis was a ex-factory ailing district. Field site visit, deep interview with professionals and citizens, walk through observation, and historial literature review on the site were employed. As results, its history, retrofit process and current change were systematically described. The results showed ways of thinking, attitude toward historic preservation, technology, and creativity of using existing buildings for contemporary functions. This has a significant implication on Korean urban development which mostly, has ignored the existing value of community and buildings.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.83-90
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• 2010

The purpose of this study is to establish the standard of fire lane design to improve the performance of disaster prevention in local area. To accomplish it, we have focused on three research methods as below: first, we have expected disaster occurrence based on emergency tendency in local area; second, we have verified fire lane routes design through fire lane modeling and network analysis; third, we have quantitatively examined a possibility of danger of fire lanes through current road network modeling and analysis. The result of this study could be helpful to effective fire lane designs and quantitative analyses.

• Journal of the Korea Society of Computer and Information
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• v.11 no.6 s.44
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• pp.157-164
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• 2006

From the hazard which it prepares in the hazards increase which it follows in information demand augmentation of information technical development and the consumer from inside systematizing integrity and solubility of information technological resources. inside against a confidentiality. The control against information and a system and a data outside is demanded. From the dissertation which it sees demand function and the structure which do information technical risk management system development it will be able to manage the danger which it infiltrates with the root which is various overview in hazard necessity it investigated the inside and outside of the country instance in the center and it analyzed. And it plans the dangerous civil official integrated process model ultimately as against a hazards it will be able to prepare in the dictionary in order, it put the place objective which it induces.

• Convergence Security Journal
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• v.5 no.3
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• pp.15-22
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• 2005

The spread of Internet and the appear of Downsizing, SI(System Integration) is chaning centralized computing to distributed computing. Also distributed computing is rapidly changing to Ubiquitous computing escape from hard wire connected network. CORBA(Common Object Request Broker Architecture) is a middleware that used for smoothness communication between application program and operation system in a different environment. However distributed computing environment is not safe from the danger, the attack like virus, worm is too intellectual and variety. In this paper, we design a new DB security model and suggest efficiency of it in Ubiquitous environment base on CSS(CORBA Security Service) that present ed from OMG(Object Management Group).

• Journal of Navigation and Port Research
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• v.30 no.2
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• pp.125-130
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• 2006

Waves, which are the main source of ship motions in a seaway, considerably affect the performance of a ship. The study of waves and their impact on ship motions within harbors is an important aspect of the design and operation of harbors. The prediction of incoming groups of waves is particularly important for evaluating ship motion within a harbor. Such a prediction makes it possible to evaluate ship safety more accurately. The wave transformation model reported here is applied to actual ports based on Boussinesq wave equations both non-linear and dispersive wave processes be considered in order to capture physical effects such as wave shoaling, refractions, reflection and diffraction in variable depth environments. The prediction of incoming groups of waves is particularly important for evaluating ship motion within a harbor, Such a prediction makes it possible to evaluate ship safety more accurately and provide safe wave informations for navigation. Furthermore, a wave information support system is proposed for entering ships as one technique for improving the safety of ship operations. This system predicts the run of waves and reduces the danger by identifying the most dangerous point near the harbor entrance at the small wave groups.