• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1B
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• pp.1-10
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• 2007

We propose a new approach to accommodate bidirectional asymmetric traffic demands as well as unexpected dynamic internet traffic variation in the WDM mesh network by using optical networking technologies. In the proposed scheme, an intermediate node determines the optical path based on the switching statistics of IP router of the node which characterizes the Internet traffic variation, which in effect provides a dynamic and distributed traffic control over the network. It is expected to reduce the efficiency deterioration of RWA(Routing and Wavelength Assignment) due to the real-time variation of Internet traffic so that expandability and flexibility of the network can be enhanced. In this paper, we describe a methodology for traffic behavior analysis at a node, and the decision policy of the establishment/release of optical path. In addition, we evaluate the performance of the proposed scheme through the computer simulations.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.71-78
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• 2013

Recently, the opportunistic incremental relaying systems have been studied to improve the system performance effectively in wireless fading channel. Most of the performance analysis of the system includes a source-destination direct link. And there are few analysis which consider source-relay-destination indirect paths only. Therefore this paper proposes a transmission protocol which relays the source information using the selected relay from the partial channel information at the first stage in an opportunistic incremental relaying system. If the transmission fails, the selected best relay from the full channel information retransmits the information to the destination incrementally. The performance of the proposed system is derived analytically and verified from Monte Carlo simulation. The derived results can be applied to the system design and the performance estimation of the mobile systems and the bidirectional TV broadcasting systems which adapt an opportunistic incremental relaying system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5C
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• pp.163-170
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• 2011

Perimeter load transfer functions were developed by an analysis of the static pile load test results of the 7 large diameter drilled shafts constructed in domestic areas. Using the pile axial load distributions obtained from the static pile load tests of large diameter drilled shafts, the unit skin frictions were analyzed and, based on unit skin friction test data, perimeter load transfer functions could be suggested. The load transfer distributions calculated by suggested functions and the load transfer functions obtained from the bi-directional pile load tests were compared. As a result, the 2 load transfer distributions were coincided, respectively.

• The Korean Journal of Applied Statistics
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• v.26 no.1
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• pp.23-36
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• 2013

In this study, we investigate how churn customers (who play a central connector or broker role) affect other customers' churn in their call networks with ego-network analysis using call data of a mobile telecom company in Korea. As a result of investigating Reciprocal Network, we found a relationship of attrition among churn customers. Churn provokers who influence other customers' attrition exist in customer churn networks. The characteristics of churn provokers is that they play a central connector and broker role in their groups. The proportion of churn provokers increases and the churn provoker's influence increases because the network is a reciprocal one.

• The Journal of Society for e-Business Studies
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• v.17 no.2
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• pp.105-114
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• 2012

Recently, global warming, energy shortage, and environmental disruption have been serious problems in every nation. It became more and more important to reduce the emission of CO2 and to use of energy efficiently. Smart grid was also introduced using the rapidly developing information technology. It deployed the mutual communication concept between customers and the suppliers in the electricity supply. There were increasing demands to adopt the smart meter and to present incentive for efficient energy usage in many developed countries. The objective of this research was to develop the optimal real time pricing model which maximized the profit of the power retailer and reduced the usage of energy. The simulation study was given to show the usefulness of the model. Simulation considered the customer demand response rate and price elasticity rate. The price elasticity rate was compared in the condition of fixed value according to time and variable value according to the customers. The optimal price model could maximize the profit of the power retailer and reduce the energy usage of the consumers.

• Environmental and Resource Economics Review
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• v.19 no.3
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• pp.485-508
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• 2010

This paper examines the long memory property and investigates cointegration in the dynamics of crude oil markets. For these purposes, we apply the joint ARMA-FIAPARCH model with structural break and the vector error correction model (VECM) to three daily crude oil prices: Brent, Dubai and West Texas Intermediate (WTI). In all crude oil markets, the property of long memory exists in their volatility, and the ARMA-FIAPARCH model adequately captures this long memory property. In addition, the results of the cointegration test and VECM estimation indicate a bi-directional relationship between returns and the conditional variance of crude oil prices. This finding implies that the dynamics of returns affect volatility, and vice versa. These findings can be utilized for improving the understanding of the dynamics of crude oil prices and forecasting market risk for buyers and sellers in crude oil markets.

• Journal of Convergence for Information Technology
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• v.10 no.7
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• pp.41-48
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• 2020

Recently, the spreading business of AMI (Advanced Metering Infrastructure) remote metering systems in various regions of the country has been activated, and it provides various metering functions such as two-way communication and security plan functions for power demand management. Current AMI system is difficult to analyze based on the existing RDB(Relational Database) due to the increase in the size of new internal IoT devices and networks. This study proposes a new GDB(Graph Database) based failure analysis method that utilizes existing RDB data. It analyzes the correlation of new failure patterns through accumulated data such as internal thresholds and status values. As a result of GDB-based simulation, it was confirmed that RDB can predict to a new obstacle pattern that was difficult to analyze.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.1
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• pp.63-68
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• 2004

In this paper, we propose a method about the extraction of vehicle and tracking trajectory for moving vehicle tracking system in road. This system applied to the monitoring system of the traffic flow for ATMS(advanced traffic management system) of ITS(intelligent transport system). Also, this system can solve the problem of maintenance of loop sensor. And we detected vehicle using differential image analysis. Because of the road environment changes by real time. Therefore, the method to use background image is not suitable. And we used Kalman filter and innovation value and variable search area for vehicle tracking system. Previous method using fixed search area is sensitive to the moving trajectory and the speed of vehicle. Simulation results show that proposed method increases the possibility of traffic measurement more than fixed area traffic measurement system.

• Archives of design research
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• v.17 no.3
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• pp.449-460
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• 2004

Various types of the sports utility vehicles become more popular in these days. This phenomenon says the increasing demand of performance oriented vehicles for the various life style It is changing now the rather the simple needs of passenger cars of the past. This popularity is due to not only for the increased leisure time which resulted from the five day working labor policy, but also the development of automotive technology. In addition to a large variety of vehicle and enhanced performance is another reason either. There have been many kind of multi-functional vehicles from the early days of the automotive history, and most of them have been evolved from the $\ulcorner$Jeep$\lrcorner$ which were developed by American makers. And various type of orthodox and crossover vehicles that is combined to many functional aspects for a transportation has been revealed so far. Usually the ambi-tendency has been revealed, in which the crossover vehicle has been become compact, on the other hand the orthodox type of 4-wheel drive vehicles has been become larger for being heavy duty vehicles. And this would be expand widely to more vehicles and brands in the future.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.641-641
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• 2015

수자원 관리의 새로운 패러다임으로 스마트워터그리드가 이슈화되고 있다. 스마트워터그리드는 현재 직면해 있는 물 문제를 ICT기술을 활용하여 효율적으로 관리 및 운영할 수 있는 기술이다. 가뭄과 홍수 등을 대응하기 위한 분산형 수자원, 그리고 수량과 수질등의 통합 관리를 지향하는 물관리 패러다임과 ICT와 물산업을 융복합화하여 양방향 실시간 운영을 통한 네트워크 구성, 그리고 대규모 수원개발과 장거리 수송방식으로부터 지역단위의 부존된 수자원인 다중수원을 효율적으로 활용하고, 이들 수원의 최적 블랜딩 기술 및 멀티워터루프를 이용한 수요자 중심의 물관리에 초점을 맞추고 있다. 이에 본 연구에서는 지역의 부존된 수자원을 효율적으로 관리하기 위한 운영지수를 산정함으로써 지역의 평상시 물관리 운영과 상수공급차단, 다중수원에 오염물질 유입, 가뭄발생 등 비상시 상황에 물관리가 원활히 이루어지도록 하였다. 스마트워터그리드에서 사용되는 물관리 운영지수는 비상시 지역간 플랫폼에 정상적으로 물공급이 어렵거나, 예상되어 유량 확보가 필요시 원활하게 유량 확보가 가능하도록 주변 지역간의 운영지수를 산정하여 최적의 조건을 도출하여 우선순위를 시나리오에 나타내어 사용자가 플랫폼에 물공급이 가능하도록 제시한 운영지수이다. 물관리 운영지수는 중회귀분석 기법을 이용하여 종속변수에 선형적인 영향을 미치는 유량, 수질, 이송거리, 전력비용, 경제적인 영향 등을 고려하여 종속변수의 값을 예측하고 통계적인 기법으로 유량, 수질, 이송거리, 전력비용, 경제적인 영향 등에 대한 장래추정치를 부여하여 회귀모델을 구축하여 물관리 운영지수를 산정하였다. 이를 활용하여 평상시에는 물수요 공급량을 정확히 관리하여 지역간의 수자원 불균형을 해소하고 비상시에는 상황을 대처하여 지역의 물부족 문제를 해소할 수 있을 것으로 판단된다.