• 한국정보통신학회논문지
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• 제13권9호
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• pp.1935-1940
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• 2009

WSN(Wireless Sensor Network)의 기술 요소 중의 하나는 센서 노드의 위치 관리이다. GPS, 초음파 센서, RSSI 등이 전형적인 노드의 위치 관리 방법이다. 본 논문에서는 센서 노드 위치 측정의 정확성을 향상시키기 위해 RSSI 측정에 회귀분석을 적용한 새로운 위치 관리 방식을 제안한다. 또한 기존 방식의 실험적인 결과와의 비교를 통해 제안된 방식의 성능을 평가한다. 결과에 따르면 우리 의 제안된 방식인 LM-RAR은 RSSI와 Friis 공식을 사용한 기존의 위치 관리 방식보다 향상된 정확성을 보인다.

• 대한산업공학회지
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• 제23권4호
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• pp.825-833
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• 1997

The purpose of this paper is to develop a method of postoptimality analysis that can be applied to an optimal solution of a maximum flow problem. We first use the transformed network corresponding to a given network. In such a network we conduct postoptimality analysis by determining changes in the optimal solution precipitated by changes in the capacity as the arc capacity varies from 0 to infinite. By this method we can easily calculate not only the characteristic region where the given optimal solution remains unchanged, but also the characteristic region where the value of the maximal flow gradually increases or decreases. The proposed method is demonstrated by numerical example.

• 산업경영시스템학회지
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• 제17권32호
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• pp.53-62
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• 1994

This paper deals with the analysis of the PC communication service system performance which will be installed as a gateway between PSTN and PSDN. Firstly, we classify the data traffic pattern into interactive, conversational, and file transfer type from the actual statistics. Secondly, we model the system structure as a closed queueing network model with multiservers and multiple customer classes and derive the analytic method to be able to measure the system performance using Mean Value Analysis. Finally, the simulation results indicate that the analytic method obtained is a good approximation method to measure the system performance of the PC communication service system as a gateway between PSTN and PSDN.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권6호
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• pp.1649-1667
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• 2012

In order to improve the accuracy and universality of the flow metric correlation analysis, this paper firstly analyzes the characteristics of Internet flow metrics as random variables, points out the disadvantages of Pearson Correlation Coefficient which is used to measure the correlation between two flow metrics by current researches. Then a method based on Symmetrical Uncertainty is proposed to measure the correlation between two flow metrics, and is extended to measure the correlation among multi-variables. Meanwhile, the simulation and polynomial fitting method are used to reveal the threshold value between different correlation degrees for SU method. The statistical analysis results on the common flow metrics using several traces show that Symmetrical Uncertainty can not only represent the correct aspects of Pearson Correlation Coefficient, but also make up for its shortcomings, thus achieve the purpose of measuring flow metric correlation quantitatively and accurately. On the other hand, reveal the actual relationship among fourteen common flow metrics.

• 대한전기학회논문지:전력기술부문A
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• 제49권12호
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• pp.602-607
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• 2000

This paper presents the new simulation algorithms using network methods to analysis the steady-state train voltage distribution characteristics in ac auto-transformer fed railroads. In general, the supply system of railroads is composed of non-symmetrical and unbalance transmission line. Therefore, the general method using simplified old algorithms have the self-contradictory errors because the supply line of train railroads is completely unbalanced. In this paper, the simulation results of new developed algorithms is compared with those of EMTP to confirm the effectiveness.

• Journal of Information Processing Systems
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• 제15권3호
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• pp.616-631
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• 2019

With the rapid increase of information on the World Wide Web, finding useful information on the internet has become a major problem. The recommendation system helps users make decisions in complex data areas where the amount of data available is large. There are many methods that have been proposed in the recommender system. Collaborative filtering is a popular method widely used in the recommendation system. However, collaborative filtering methods still have some problems, namely cold-start problem. In this paper, we propose a movie recommendation system by using social network analysis and collaborative filtering to solve this problem associated with collaborative filtering methods. We applied personal propensity of users such as age, gender, and occupation to make relationship matrix between users, and the relationship matrix is applied to cluster user by using community detection based on edge betweenness centrality. Then the recommended system will suggest movies which were previously interested by users in the group to new users. We show shown that the proposed method is a very efficient method using mean absolute error.

• Journal of Information Processing Systems
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• 제19권3호
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• pp.323-333
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• 2023

Facial expression recognition can aid in the development of fatigue driving detection, teaching quality evaluation, and other fields. In this study, a facial expression recognition method was proposed with a residual masking reconstruction network as its backbone to achieve more efficient expression recognition and classification. The residual layer was used to acquire and capture the information features of the input image, and the masking layer was used for the weight coefficients corresponding to different information features to achieve accurate and effective image analysis for images of different sizes. To further improve the performance of expression analysis, the loss function of the model is optimized from two aspects, feature dimension and data dimension, to enhance the accurate mapping relationship between facial features and emotional labels. The simulation results show that the ROC of the proposed method was maintained above 0.9995, which can accurately distinguish different expressions. The precision was 75.98%, indicating excellent performance of the facial expression recognition model.

• 전기전자학회논문지
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• 제23권2호
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• pp.659-666
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• 2019

MANET은 이동 노드들로 망을 자율적으로 구성할 수 있어 다양한 응용에서 적용되고 있다. 그러나 중앙의 제어나 관리 없이 분산 환경으로 망을 구성하여 사이버 공격에 취약할 수 있다. 본 논문에서는 시뮬레이션 환경에서 MANET 보안 취약점을 분석하고 검증할 수 있는 방안을 제안한다. 또한, 제안하는 방안을 적용하여 MANET에서 빈번하게 발생할 수 있는 라우팅 메시지 변조 공격, 거짓 노드 공격, TLV 메시지 변조 공격에 대하여 모의하고, 실 시스템에서도 유사한 취약점이 발생함을 확인하였다. 따라서 제안하는 방안은 사이버 공격자에 의해 발생 가능한 보안 취약점을 통신망 기술을 설계하는 과정에서 시뮬레이션을 통하여 검증함으로써 통신 기술 설계 정확도를 향상시키는데 활용될 것으로 예상된다.

• 한국콘텐츠학회논문지
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• 제20권2호
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• pp.96-104
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• 2020

온라인 쇼핑몰의 활성화로 소비자들의 소비 활동이 활발해짐에 따라 기업들은 매출 증대를 위해 소비자의 상품 트렌드 분석을 수행하고 있다. 기존의 상품 트렌드 분석 기법들은 온라인 쇼핑몰 사용자의 활동만을 고려하여 분석하기 때문에 구매 이력이 없거나 새로운 상품에 대한 트렌드를 파악하기 어렵다. 본 논문에서는 쇼핑몰에서 사용자의 트렌드와 잠재적 고객의 트렌드를 분석하기 위해 온라인 쇼핑몰 데이터와 소셜 네트워크 데이터를 결합한 트렌드 분석 기법을 제안한다. 제안하는 기법은 서비스 내 데이터 분석을 위해 사용자의 활동로그를 분석하고 활동 로그가 없는 잠재적인 사용자들의 관심도를 반영하기 위해 소셜 네트워크 데이터에서 단어 집합 추출을 통해 생성한 핫 토픽을 결합하였다. 최종적으로 상품 지수와 소셜 네트워크에서의 언급수를 활용하여 시간에 따른 상품 트렌드 변화를 탐지한다. 소셜 네트워크 데이터를 활용한 성능 평가를 통해 제안하는 기법의 우수성을 입증한다.

• 기술혁신학회지
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• 제3권3호
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• pp.36-52
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• 2000

This study takes an issue of efficiency analysis in the presence of network effect utilizing the DEA (Data Envelopment Analysis) framework. Network effect has important policy implication for the regulation of local monopolies which undertake their business through physical network, such as electricity, natural gas, local telephony, etc. If the difference in spatial condition between companies is not controlled properly, the performance comparison and associated incentive regulation bear significant bias. In this study, we propose a methodology to measure the true managerial or technical efficiency apart from efficiency difference accruing from the difference in spatial condition. A series of modified DEA efficiency models are combined to investigate the extent of exogenous and endogenous efficiency component in the Korean natural gas distribution companies. Empirical results show that the network effect plays significant role in determining superficial performance difference.