• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.1005-1015
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• 2020

This paper aims to propose a Comprehensive Decision Support Model to evaluate retail companies' financial performance traded on the Vietnam Stock Exchange Market. The financial performance has been examined in terms of the valuations ratios, profitability ratios, growth rates, liquidity ratios, efficiency ratios, and leverage ratios. The data of twelve companies from the first quarter to the fourth quarter of 2019 and the first quarter of 2020 were employed. The weights of 18 chosen financial ratios are calculated by using the Standard Deviation method (SD). Grey Relational Analysis technique was applied to obtain the final ranking of each company in each quarter. The results showed that leverage ratios have the most significant impact on the retail companies' financial performance and gives some long-term investment recommendations for stakeholders and indicated that the Taseco Air Services Joint Stock Company (AST), Mobile World Investment Corporation (MWG), and Cam Ranh International Airport Services Joint Stock Company (CIA) are three of the top efficient companies. The three of the worst companies are Viglacera Corporation (VGC), Saigon General Service Corporation (SVC), and HocMon Trade Joint Stock Company (HTC). Furthermore, this study suggests that the GRA model could be implemented effectively to ranking companies of other industries in the future research.

• Journal of Korea Port Economic Association
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• v.20 no.1
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• pp.123-140
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• 2004

With the globalization of economy, there is keen competition among rountries to be a logistics hub and companies are striving to be first in establishing logistics system centering on advantageous sites, especially airport and seaports, to perform supply, production and distribution. Korea competing with Northeast Asia countries is also working out strategies in order to make Korea peninsula a logistics center of Northeast Asia taking advantage of its geographical strength. Gwangyang port has designated as Free Economic Zone together with Pusan and Jinhae, Incheon from October 24th, 2003. However, the introduction of Free Economic Zone in Korea lagged behind other major countries and it has a lot of operational problems. Approximately 600 areas worldwide are designated and operated as a Free Economic Zone and Gwangyang port and its surrounding area has several points to be settled as one of FEZ. First one is its limited functions and related laws. Next is imperfection on development, investment and management system of the hinterland. Lark of promotion activities could be one of the problems. This paper analyzes the above problems and presents various measures to activate Gwangyang Port and Gwangyang Free Economic Zone as follows Benchmarking to promote Gwangyang Free Economic Zone as follows Benchmarking other countries' system, governmental support, introduction & logistics functions, early development of the hinterland, supply of effective one-stop service, investment attraction into the area and diversified promotion & marketing activities.

• Journal of Environmental Impact Assessment
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• v.20 no.1
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• pp.25-36
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• 2011

In this study, the accurate water quality analysis in rivers, including the non-point source is performed. First of all, watershed model, SWAT(Soil and Water Assessment Tool) was applied to analyze the impact of the non-point source in study area. And then, water quality analysis integrating the point source and the non-point source is implemented using QUALKO model. For more exact simulation, it should be the calibration and verification of variables and parameters which are needed for simulation. In addition, the importance of considering the non-point source was confirmed in river water quality simulation. BOD, TN, TP were analysed, and the results shows that BOD, TN and TP concentration was increased to 16.8%, 8.2% and 25.8% respectively. The more accurate estimate will be carried if use of reliable measurements and watershed simulation be done in models linking process. The suggested technique will improve the accuracy of the water quality analysis. The methodologies presented in this study will contribute to basin-wide water quantity and quality management.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.1
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• pp.130-135
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• 2014

FOD(Foreign Object Debris) has the potential threat to damage aircraft during critical phases of take-off and landing roll with some objects including metal on the runway. FOD can be found anywhere on an airport's air operation areas such as runway, taxiway and apron. It can lead to catastrophic loss of life and airframe, and increased maintenance and operating costs. In this paper, we defined FOD and surveyed its riskiness and necessity of automatic FOD detection system. We compared the requirements of the environment in Korea to the FAA advisory circular. Also we analyzed operation methods of FOD detection systems already installed at some airports. Based on the surveys mentioned above, we propose hybrid type of FOD detection system considering the environment in Korea which uses millimeter wave radar, optical camera and thermal imaging camera to detect FOD efficiently. In management approach, fixed type of the system should be installed for real-time monitoring, and mobile type of the system can be used additionally.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.136-151
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• 2016

Flexible large-scale WLANs are now widely deployed in crowded and highly mobile places such as campus, airport, shopping mall and company etc. But network management is hard for large-scale WLANs due to highly uneven interference and throughput among links. So the traffic is difficult to predict accurately. In the paper, through analysis of traffic in two real large-scale WLANs, Granger Causality is found in both scenarios. In combination with information entropy, it shows that the traffic prediction of target AP considering Granger Causality can be more predictable than that utilizing target AP alone, or that of considering irrelevant APs. So We develops new method -Granger Causality and Vector Auto-Regression (GCVAR), which takes APs series sharing Granger Causality based on Vector Auto-regression (VAR) into account, to predict the traffic flow in two real scenarios, thus redundant and noise introduced by multivariate time series could be removed. Experiments show that GCVAR is much more effective compared to that of traditional univariate time series (e.g. ARIMA, WARIMA). In particular, GCVAR consumes two orders of magnitude less than that caused by ARIMA/WARIMA.

• Journal of the Korean Society of Safety
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• v.31 no.4
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• pp.15-21
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• 2016

The elevator is an essential part of the transportation means in modern society. It has become the convenient movement means of vertical and horizontal mobilities for vulnerable citizens including the disabled or elderly in skyscrapers and the multi-purposes facilities. After the 1990s, the number of newly installed elevators have increased because of the establishment of large scale public houses which need an increase of means of transportation. Thus, the safety accident in the elevator has been currently in an increasing trend as years passed by because that the elevator is always exposed to the risk of accident. Most of the elevator accidents occur in the escalator and moving walkway. This study investigated the current usage situations of users at multi-purpose shopping spaces, the sub way, and the airport about the escalator including moving walkway. Moreover the accident types were analyzed for the escalator based on 10 years of statistics. And the methods for the accident prevention were proposed on the equipment, management and user side.

• Journal of the Korea Society of Computer and Information
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• v.21 no.3
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• pp.113-121
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• 2016

In this study, the basic concept of service profit chain was introduced based on the existing studies related to service quality of airline ground crew to find out how are customer satisfaction influenced by factors related to employees who provide service quality to the customers, such as internal service quality and job satisfaction. The data of this study was collected by questionnaire and based on airline ground crews and Gimpo international airport users. A total of 190 of airline ground crew and 273 of passengers validity sample was analyzed a frequency analysis, reliability analysis, exploratory factor analysis and correlation coefficient analysis from SPSS 21, a hypothesis through out confirmatory factor analysis and structural equation modeling from AMOS 7.0. As a result of the analyses, it was found that the models was appropriate in proving the hypotheses on interrelationships among internal service quality, job satisfaction and customer satisfaction. Overall, finding of this study enhance the theoretical progress on the experiential concept in walking tour and offer important implication for airline industry marketers.

• Journal of Information Technology Applications and Management
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• v.20 no.1
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• pp.87-106
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• 2013

This study is to explore the airline network patterns of Incheon and Narita International Airports using passenger flight departure and arrival data of the two airports. The so-called Origin-Destination data is collected from the airports' websites and some of the important data items are flight number, city of origin, destination city, departure/arrival time, number of flights, and delay time. A snowflake schema dimensional model is proposed and implemented. Tableau Public, a well-known visual analytic tool, is used to connect the dimensional model and played an important role in navigating the data space to find interesting and visual patterns among corresponding airports and airlines. For the efficiency of analyzing this spacious data mart, data visualization method was used. Four types of visualization method proposed by Yau was used; visualizing patterns over time, visualizing proportions, visualizing relationships, and visualizing spatial relationships. The strength of connectivity of each flight segments is calculated to evaluate the degree of globalization of Seoul and Tokyo. We anticipate that various patterns and new findings produced by the data mart would provide airline managers, airport authorities, and policy makers in the field of travel and transportation with insightful information.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.315-323
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• 2015

Nowadays, it is expected that mobility loads such as electric railways and electric vehicles will be penetrated gradually and affect on the power system stability by their load characteristics. Various researches have been carried out about electric vehicles for the recent decade though the load of electric railway could be forecasted because of the specified path and timetable, is a field with a long historic background. Some precise 5th polynomial equations are required to analyze the power system stability considering mobility load to be increased in the immediate future while the electric railway dispatching simulator uses load models with constant power and constant impedance for the system analysis. In this paper, seasonal urban railway load models are established as the form of 5th polynomial equations and substation load modeling methods are proposed merging railway station load models and general load models. Additionally, load management effects by the load modeling are confirmed through the case studies, in which seasonal load models are developed for Seoul Subway Line No. 2, Gyeongui Line and Airport Railroad and the substation load change is analyzed according to the railway load change.

• Smart Structures and Systems
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• v.26 no.2
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• pp.241-251
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• 2020

Due to the undeniable importance of approximating the concrete compressive strength (CSC) in civil engineering, this paper focuses on presenting four novel optimizations of multi-layer perceptron (MLP) neural network, namely artificial bee colony (ABC-MLP), grasshopper optimization algorithm (GOA-MLP), shuffled frog leaping algorithm (SFLA-MLP), and salp swarm algorithm (SSA-MLP) for predicting this crucial parameter. The used dataset consists of 103 rows of information concerning seven influential parameters (cement, slag, water, fly ash, superplasticizer, fine aggregate, and coarse aggregate). In this work, the best-fitted complexity of each ensemble is determined by a population-based sensitivity analysis. The GOA distinguished its self by the least complexity (population size = 50) and emerged as the second time-effective optimizer. Referring to the prediction results, all tested algorithms are able to construct reliable networks. However, the SSA (Correlation = 0.9652 and Error = 1.3939) and GOA (Correlation = 0.9629 and Error = 1.3922) performed more accurately than ABC (Correlation = 0.7060 and Error = 4.0161) and SFLA (Correlation = 0.8890 and Error = 2.5480). Therefore, the SSA-MLP and GOA-MLP can be promising alternatives to laboratorial and traditional CSC evaluative methods.