• Journal of KIISE:Information Networking
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• v.35 no.3
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• pp.173-182
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• 2008

Promoting quality of streaming service in wireless networks has attracted intensive research over the years. Instable wireless channel condition causes high transmission delay and packet loss, due to fading and interference. Therefore, they lead to degrade quality of video streaming service. The IEEE 802.11 Working Group is currently working on a new standard called IEEE 802.11e to support quality of service in WLANs. And several schemes were proposed in order to guarantee QoS. However, they are not adaptable to network condition. Accordingly, they suffered video quality degradation, due to buffer overflow or packet loss. In this paper, to promote quality of video streaming service in WLANs, we propose a cross-layer architecture based on IEEE 802.11e EDCA model. Our cross-layer architecture provides differentiated transmission mechanism of IEEE 802.11e EDCA based on priority of MPEG-4 video frames and adaptively controls the transmission rate by dropping video frames through the efficient bandwidth estimation based on distinction of each AC. Through the simulation, proposed scheme is shown to be able to improve end-to-end qualify for video streaming service in WLANs.

• Journal of Intelligence and Information Systems
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• v.20 no.4
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• pp.43-58
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• 2014

As the use of trading systems has increased rapidly, many researchers have become interested in developing effective stock market prediction models using artificial intelligence techniques. Stock market prediction involves multifaceted interactions between market-controlling factors and unknown random processes. A successful stock prediction model achieves the most accurate result from minimum input data with the least complex model. In this research, we develop a combination model of ${\pi}$-fuzzy logic and support vector machine (SVM) models, using a genetic algorithm to optimize the parameters of the SVM and ${\pi}$-fuzzy functions, as well as feature subset selection to improve the performance of stock market prediction. To evaluate the performance of our proposed model, we compare the performance of our model to other comparative models, including the logistic regression, multiple discriminant analysis, classification and regression tree, artificial neural network, SVM, and fuzzy SVM models, with the same data. The results show that our model outperforms all other comparative models in prediction accuracy as well as return on investment.

• The Transactions of the Korea Information Processing Society
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• v.3 no.1
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• pp.127-143
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• 1996

Advanced countries are very active in deploying the National Information I infrastructure which provides universal service to promise fruitful quality of futuree life. Even in the distributed environment, we can closely converse, work together, and share information in a very convenient way. This is actually enabled with the help of groupware technology, which are currently focused and researched in a larger popularity. The aim of this study is to design a portable pack for group communications management to support the development of groupware application. In the paper we begin with technical survey, continue to build our own model for group communications man agement, and design its architecture and procedure. We also suggest group addressing mechanism under Internet environment such as how to create IP multicast address and IP port number dynamically and as a globally unique value for the communication session, with the help of the hierarchical and distributed address managers. We also indicate the reliable data transmission services to remedy the unreliable feature of the UDP multicast services, and finally the architecture/ applied to support the practical applications is briefly discussed for verification of the designed concept.

• Journal of KIISE:Software and Applications
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• v.31 no.9
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• pp.1226-1232
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• 2004

Biometric authentication is rising technology for the security market of the next generation. But most of biometric systems are developed using only one of various biological features. Recently, there is a vigorous research for the standardization of various biometric systems. In this paper, we propose a web-based authentication system using three other verifiers based on functional, parametric, and structural approaches for one biometrics of handwritten signature, which is conformable to a specification of BioAPI introduced by BioAPI Consortium for a standardization of biometric technology. This system is developed with a client-server structure, and clients and servers consist of three layers according to the BioAPI structure. The proposed neb-based multiple authentication system of one biometrics can be used to highly increase confidence degree of authentication without additional several biological measurements, although rejection rate is a little increased. That is, the false accept rate(FAR) decreases on the scale of about 1:40,000, although false reject rate(FRR) increases about 2.7 times in the case of combining above three signature verifiers. So the proposed approach can be used as an effective identification method on the internet of an open network. Also, it can be easily extended to a security system using multimodal biometrics.

• Journal of radiological science and technology
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• v.36 no.3
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• pp.193-200
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• 2013

There are many concerns about radiation exposure in Korea after Fukushima Nuclear Plant Accident on 2011 in Japan. As some isotope materials are detected in Korea, people get worried about the radioactive material. In addition, the mass media create an air of anxiety that jump on the people's fear instead of scientific approach. Therefore, for curbing this flow, health, medical institute from the world provide a variety of information about medical radiation safety and hold the campaign which can give people the image that medical radiation is safe. At this, the Korean Food and Drug Administration(KFDA) suggested that make the alliance of medical radiation safety and culture on August, 2011. Seven societies and institutions related medical radiation started to research and advertise the culture of medical radiation safety in Korea. In this report, mainly introduce the activities of the Korean Alliance for Radiation Safety and Culture in Medicine(KARSM) for spreading culture of medical radiation safety from 2011 to 2012.

• Journal of Broadcast Engineering
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• v.12 no.2
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• pp.148-158
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• 2007

Recently, IEEE 802.15.4a(low-rate UWB) technique has been paid much attention to the LR-UWB communication system for WPAN. However, there are various interferences such as MPI(Multi Path Interference) or IPI(Inter Piconet Interference) in IEEE 802.15.4a wireless channel. In order to cancel various interferences occurred to WPAN environment, in this paper, we propose a UWB wireless communication system with high QoS(Quality of Service) which is a chaotic-OOK(On-Off Keying) system using unipolar ZCD(Zero Correlation Duration) spreading code in physical layer level. Furthermore, we analyze its performance via simulations and verify the availability of proposed system with prototype implementation.

• Journal of Bio-Environment Control
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• v.27 no.1
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• pp.20-26
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• 2018

This study was conducted to develop a device for measuring the air flow by space variation through monitoring program, which acquires data by each point from each environmental sensor located in the greenhouse. The distribution of environmental factors(air temperature, humidity, wind speed, etc.) in the greenhouse is arranged at 12 points according to the spatial variation and a large number of measurement points (36 points in total) on the X, Y and Z axes were selected. Considering data loss and various greenhouse conditions, a bit rate was at 125kbit/s at low speed, so that the number of sensors can be expanded to 90 within greenhouse with dimensions of 100m by 100m. Those system programmed using MATLAB and LabVIEW was conducted to measure distributions of the air flow along the greenhouse in real time. It was also visualized interpolated the spatial distribution in the greenhouse. In order to verify the accuracy of CFD modeling and to improve the accuracy, it will compare the environmental variation such as air temperature, humidity, wind speed and $CO_2$ concentration in the greenhouse.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.1
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• pp.61-71
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• 2017

Local festival in Korea has developed quantitatively as well qualitatively. Driving force of local festival's development is local governments' active supports. Many Local government support local festival opening actively to accomplish economic activation. Activation of local festivals is good chance to local start-up companies. Local start-up companies don't have well known brand, and wide distribution network. But they can sell their products to visitors in local festival. And if fortune smiles upon them, they can get big buyers in local festivals. If so, what factors can contribute to a increase sales of local start-up companies? Different from existing research that focus on tour industrial outcome, we will focus on effect of festival service quality on increase sales. The survey is using structured questionnaire, we surveyed visitors who visit local start-up companies' booth in festival site. According to survey result, first, each dimensions of festival service quality do not effect on purchase intention directly except empathy dimension. Second, each dimensions of festival service quality effect on purchase intention by a medium of local image indirectly except assurance dimension. And purchase intention have a great effect on purchase action. Through the results, we can confirm festival service quality effect on purchase intention by a medium of local image indirectly. we suggest that improving festival service quality can effect on sales increase of local start-up companies, and for the purpose of sales increase, local government must improve local image at first.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.5
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• pp.141-162
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• 2017

The International Monetary Fund (IMF) crisis introduced a system for easy layoffs. With recent economic downturn, employees have been asked to retire early and less new jobs have become available. More small businesses as a result have been started. The purpose of this research is to study weight and ranking on SWOT factors of korea food service franchise industry using the SWOT analysis. The Analytic Hierarchy Process (AHP) and Analytic Network Process (ANP) were used to analyze the SWOT found by the surveys. First, the SWOT analysis shows that the franchise owners and the expert group view the industry positively overall and there are more strengths, opportunities than weaknesses, threats. While there are negatives and threats to the industry overall, many people think that there are more opportunities and positive aspects. Second, the franchise owners rank proven business model and platform (S3) as the strongest strength of food service franchise businesses while the expert group ranks management supports (S2) from headquarters as the strongest strength. Third, the expert group and franchise owner group indicate that the weight on unfair franchise contracts with headquarters(W3) and high penalty from breaking a franchise agreement(W4) are 60% of weaknesses. Fourth, both the expert group and franchise owner group indicate that change in people's lifestyle, value system and consumption pattern(O3) as the most important opportunity. Fifth, both groups indicate that changes in consumption pattern(T1) due to ever changing food service industry as the biggest threat. It is ranked higher than the entry of korea food service franchises.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.4
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• pp.637-644
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• 2016

This study sought to reevaluate the water supply capacities of the Nakdong river dams, and identify measures to remedy any shortages using weirs, focusing on 5 multipurpose dams and 8 weirs. The reevaluation of the dams was performed by the HEC-5 program using the original design criteria and inflow data recorded for each dam. The results show that the capacities of the 3 dams has decreased to 73~87%. Three simulations were performed to determine the effect of coordinating the dams and weirs. The first simulation was based on individual operation of the dams; the second on coordinated operation of the dams; and the third on coordinated operation of the dams and weirs. To obtain a water supply reliability of 95%, the annual water shortage was calculated for a 20-year period (1992~2011). In addition, long-term runoff simulation data used in the national river basin investigation by the Ministry of Land, Infrastructure and Transportation were used with the dam discharge data, because long-term inflow data for the weirs were not available. The simulations were performed by the HEC-ResSim program, with the reservoir network divided into 2 groups based on the Waegwan water station. The results show that water supply capacity for the 3 simulations to be $2424Mm^3/yr$, $2612Mm^3/yr$ and $2734Mm^3/yr$, respectively. This indicates that coordinated operation of the dams and weirs could provide an additional water supply of $122Mm^3/yr$.