• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1681-1688
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• 2009

This paper proposes a new fault restoration method which adopts the recloser as top agent to release the problems of the data concentration and fault processing delay of the existing DAS(distribution Automation System) under the ubiquitous distribution system. In proposed method, top agent collects the data based on the multi-casting communication with the tie switches of the interconnection point, and then selects a closed switch(tie switch) to transfer the sound outage load to other feeders based on the heuristic search strategy step by step until the load transfer work is finished. Here, a new heuristic rule is developed which can guarantee the relational load balancing and line loss from the collected voltage data. Finally, the several faults are simulated for typical multi-section and multi-interconnection distribution system to prove the effectiveness of the proposed strategy, in particular, for each simulation cases, the load balancing index and line loss index of the obtained solution from the proposed method is compared with those of all of feasible solutions.

• ETRI Journal
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• v.44 no.4
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• pp.588-598
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• 2022

Since multi-access edge computing (MEC) was established as a key enabler of 5G, MEC based on 5G networks (5G MEC) has been perceived as a new business opportunity for many industry players, including telecom operators. Numerous 5G MEC cooperation announcements among companies playing their respective roles in the MEC ecosystem have been recently released. However, because of cooperative and competitive relationships among key players in the MEC ecosystem and the uncertainty of 5G MEC, the announcement of 5G MEC cooperation can negatively affect the telecom operators' firm value. This study investigates the market reaction to announcements of 5G MEC cooperation for telecom operators using an event study methodology. The empirical results show that announcements of 5G MEC cooperation have a negative impact on the telecom operators' firm value. The results also show that the early deployment of 5G networks may reduce the negative impact of 5G MEC cooperation announcements by reducing uncertainty.

• Korean Institute of Interior Design Journal
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• v.24 no.1
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• pp.169-177
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• 2015

The study aimed to classify the types of domestic dormitory furniture, and analyze the characteristics of each furniture type based on the empirical research methodology. The study consisted of literature review and field visit followed by survey and in-depth interview. The researchers collected 140 images of furniture from the web sites of 87 universities. Using affinity diagram, the dormitory furniture was classified into four different types: single fixed type, single semi-fixed type, multi fixed type, and multi semi-fixed type. The finding showed that the use of single fixed type was dominant in the domestic dormitory room, which had competitive price and easy maintenance. Both single fixed type and multi fixed type turned out to be lack of storage space. Meanwhile, both single semi-fixed type and multi semi-fixed type got the high value on the space efficiency due to the multi function. However, these two types could only be applied to a wide space enough for the furniture to be transformed and extended. The study analyzed the main characteristics of the dormitory furniture according to the type classification, and it is expected that this empirical study could work as a medium and database for the upcoming dormitory furniture design studies.

• Journal of Distribution Science
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• v.18 no.1
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• pp.5-13
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• 2020

Purpose: The purpose of this study is to examine the growth and change process of Korean cosmetic market that has grown more than three times since 2000. It also examined how the growth and decline of the cosmetics brands are related to the change of the cosmetic distribution structure. Research methodology: This study tried to classify the change of the Korean cosmetics market into four stages based on the market sales information. It analyzed the sales information of Korean cosmetic companies and the relationship with the sales of the brands by distribution channel. Results: One-brand store channel had played a leading role in the market growth, and multi-brand stores have grown and a number of brands also grew through that channel since 2013. Since 2016, multi-brand stores have continued to grow and have dominated the market beyond one-brand store channel. Conclusions: The changes in sales of domestic cosmetics companies have been classified based on the distribution channel type in four stages: the emergence of one-brand store, the growth of one-brand store channel, the growth of multi-brand store channel, and the decline of one-brand store channel. In conclusion, multi-brand store channels have recently grown in the Korean cosmetics market, and this trend is expected to continue.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.2
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• pp.56-64
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• 1998

Multi-layered perceptrons that are a nonlinear neural network model, have been widely used for various applications mainly thanks to good function approximation capability for nonlinear fuctions. However, for digital hardware implementation of the multi-layere perceptrons, the quantization scheme using "look-up tables (LUTs)" is commonly employed to handle nonlinear signmoid activation functions in the neworks, and thus requires large amount of storage to prevent unacceptable quantization errors. This paper is concerned with a new effective methodology for digital hardware implementation of multi-layered perceptrons, and proposes a "piecewise affine approximation" method in which input domain is divided into (small number of) sub-intervals and nonlinear sigmoid function is linearly approximated within each sub-interval. Using the proposed method, we develop an expression and an error backpropagation type learning algorithm for a multi-layered perceptron, and compare the performance with the quantization method through Monte Carlo simulations on XOR problems. Simulation results show that, in terms of learning convergece, the proposed method with a small number of sub-intervals significantly outperforms the quantization method with a very large storage requirement. We expect from these results that the proposed method can be utilized in digital system implementation to significantly reduce the storage requirement, quantization error, and learning time of the quantization method.quantization method.

• Nuclear Engineering and Technology
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• v.41 no.1
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• pp.1-10
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• 2009

The safe and reliable performance of fusion and fission plants depends on the choice of suitable materials and an assessment of long-term materials degradation. These materials are degraded by their exposure to extreme conditions; it is necessary, therefore, to address the issue of long-term damage evolution of materials under service exposure in advanced plants. The empirical approach to the study of structural materials and fuels is reaching its limit when used to define and extrapolate new materials, new environments, or new operating conditions due to a lack of knowledge of the basic principles and mechanisms present. Materials designed for future Gen IV systems require significant innovation for the new environments that the materials will be exposed to. Thus, it is a challenge to understand the materials more precisely and to go far beyond the current empirical design methodology. Breakthrough technology is being achieved with the incorporation in design codes of a fundamental understanding of the properties of materials. This paper discusses the multi-scale, multi-code computations and multi-dimensional modelling undertaken to understand the mechanical properties of these materials. Such an approach is envisaged to probe beyond currently possible approaches to become a predictive tool in estimating the mechanical properties and lifetimes of materials.

• Journal of Distribution Science
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• v.19 no.7
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• pp.75-85
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• 2021

Purpose: This study is focused on analyzing the key reasons why One-brand Shop has been shrinking and Multi-brand shop is rising from the perspective of the trend changes of customer behavior and distribution channel in the Korean cosmetic market. The purpose of this study is to examine the factors influencing the attractiveness of cosmetics distribution channels from a store perspective and a consumer perspective. Research methodology: This study conducted a survey to define the factors that influence the attractiveness of cosmetics distribution channels. A total of 300 samples were investigated. Results: The store factors that influence the attractiveness of the cosmetics distribution channel were product quality, shopping convenience, and store accessibility in the group of single-brand store preferences, and product diversity and store experience in the group of multi-brand store preferences. Conclusions: Core competing factors of One-brand shop include product value, shopping convenience and accessibility. In contrast, Multi-Brand shops offer core competing factors of diversified product portfolio and shop function experience. A new trend has been found that the customer segments of the price-oriented group and the pleasure-oriented group have become the mainstream segments in the Korean cosmetic market. In conclusion, Multi-brand Shops are suggesting better overall customer experiences in terms of distribution channel attractiveness and customer values.

• Wind and Structures
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• v.34 no.3
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• pp.291-301
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• 2022

Although mostly used in wind turbine market, single rotor wind turbines have problems with transportation and installation costs due to their large size. In order to solve such problems, multi-rotor wind turbine is being proposed; however, light weight design of multi-rotor wind turbine is required considering the installation at offshore or deep sea. This study proposes the systematic design process of the multi-rotor wind turbine focused on its supporting structure with simultaneous consideration of static and dynamic behaviors in an ideal situation. 2D and successive 3D topology optimization process based on the density method were applied to minimize the compliance of supporting structure. To realize the conceptual design obtained by topology optimization for manufacturing feasibility, the derived 3D structure was modified to have shell structures and optimized again through parametric design using the design of experiments and the response surface method for detail design of their thicknesses and radii. The resultant structure was determined to satisfy the stress and the buckling load constraint as well as to minimize the weight and the resultant supporting structure were verified numerically.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.249-258
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• 2013

In multi-hop ad hoc networks, multi-interface multi-channel architecture is being noticing as methodology to improve the effective bandwidth and end-to-end throughput, But since existing routing metrics designed for networks based on single-interface exactly can not reflects the nature of networks based on multi-interface multi-channel, we are not expected the effect of throughput improvement. there had been proposal of MCR that discover high throughput by using metrics such as channel diversity and interface switching cost. however, MCR have an problem that is degraded it's performance in congested networks, because it not reflects the impact of traffic load. in this paper, we propose MAMCR metric, which select high throughput paths under congested conditions by combination MCR with channel access time metric, and conform it's the effect of performance improvement by ns-2 simulation.

• Journal of the Korean housing association
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• v.17 no.4
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• pp.145-153
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• 2006

Ubiquitous space can be described as a combined space of physical space and digital space. Ubiquitous space possesses new possibilities by combining the two. The concept of ubiquitous home will bring new changes in residential space design. First of all, it makes possible for more convenient and secure home. It has to be developed along with city and town level changes as ubiquitous environment. Secondly, concept of extended space as an extension of living space becomes possible by linking with outside spaces. Thirdly, as consumer requirements for residential spaces will become more versatile by social changes, ubiquitous home can be a good means to meet these versatile consumer requirements by accommodating concept of multi-functional space and flexible space. It is quite important to predict user requirements in rapidly changing social environment and versatile personal inclinations. Instead of POE methodology which can analyze and evaluate in exiting types of designs, storytelling methodology can be used to predict and direct for future requirements of living. The methodology makes scenarios of space usage for future living and extracts design requirements for the living. The concept of intelligent space has to be introduced. It is different from digital home that only accomodate digital devices in space. In intelligent space, space itself has to be recognized as an identity that interacts human directly. Intelligent space recognize human requirements and control digital devices as a response. Multi-functional space is closely related with intelligent space that can changes for business, entertainments as well as for rests by user requirements instantly. Flexible space that also intends to meet requirements of mobility and versatility can be attained through the integration of digital technology into current physical mobile systems. Interaction design becomes integral part for ubiquitous space design along with physical design. For the residential space design, digital illiteracy has to be considered for interaction design. Instead of the concept of passive existence, space itself has to be recognized as active subsistence that reacts with human. Intuitive and natural interaction for human will be a key design element for space-human interface design.