• ETRI Journal
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• v.38 no.1
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• pp.1-8
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• 2016

A large incoherent crosstalk (IC) caused by amplified spontaneous emission (ASE) noise power from Tx-disabled optical network units and a differential path loss has been shown to degrade upstream transmission performance in time-division multiplexing passive optical networks. This paper considers the IC-induced power penalty of an upstream signal both in an XG-PON and in a TWDM-PON. We investigate the degradation of the extinction ratio and relative intensity noise through a simulation and experiments. For the XG-PON case, we observe a 9.6 dB difference in the level of ASE noise power from Tx-disabled ONUs (hereafter known simply as ASE noise) between our result and the ITU-T XG-PON PMD recommendation. We propose an optical filtering method to mitigate an IC-induced power penalty. In the TWDM-PON case, the IC-induced power penalty is naturally negligible because the ASE noise is filtered by a wavelength multiplexer at the optical line terminal. The results provide design guidelines for the level of ASE noise in both XG-PONs and TWDM-PONs.

• International Commerce and Information Review
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• v.8 no.1
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• pp.357-369
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• 2006

All over the country tries to clarify the content of 'Public Policy' in recognition and implementation of Foreign Arbitral Awards : it makes comments of the international consensus of Geneva Convention(1927), New York Convention(1958) and the UNCITRAL Model Law on Public Policy, and it takes a general view of domestic laws how they deal with Public policy and Foreign Arbitral Awards. Foreign Arbitral Awards should be appropriately respected and implementation by the courts of countries encourage parties in a legal procedure to refuse enforcement by invoking "Public Policy." In order to cope with such invocations, the purport of the above recommendation on Foreign Arbitral Awards should be internationally recognized and the exceptional circumstances should be restricted unless the International Court of Arbitral Awards is not established a Dr. Holtzmann/Schwebel brought forward. In this paper suggests the list of the exceptional circumstances. Korean Arbitration Law stipulates as the Civil proceeding Law did, "good morals and the social order of the Republic of Korea" as a ground for refusing enforcement of Arbitral Awards. Studies on counteraction against invocations of Public Policy to refuse enforcement of Foreign Arbitral Awards should be developed.

• IEMEK Journal of Embedded Systems and Applications
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• v.4 no.3
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• pp.139-147
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• 2009

This paper proposed the context awareness reasoning system to provide the personalized services dynamically in a ubiquitous mobile environments. The proposed system is designed to provide the personalized services to mobile users and consists of the context aggregator and the knowledge manager. The context aggregator can collect information from networks through Open API Gateway as well as sensors in a various ubiquitous environment. And it can also extract the place types through the geocoding and the social address domain ontology. The knowledge manager is the core component to provide the personalized services, and consists of activity reasoner, user pattern learner and service recommender to provide the services predict by extracting the optimized service from user situations. Activity reasoner uses the ontology reasoning and user pattern learner learns with previous service usage history and contexts. And to design service recommender easy to flexibly apply in dynamic environments, service recommender recommends service in the only use of current accessible contexts. Finally, we evaluate the learner and recommender of proposed system by simulation.

• The Journal of the Acoustical Society of Korea
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• v.16 no.1
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• pp.67-75
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• 1997

In this paper, A method is proposed to analyze the noise figure for some parameters based on IS-98 recommendation when a RF receiver for the CDMA mobile station is designed. Simulation results show that the maximum noise figure of the receiver, which fits in the receiving sensitivity of the mobile station, is about 11dB, and this value is smaller about 3dB than the existing specification. In addition, we have tested the relationship between frame error rate and Eb/Nt of traffic channel for each coding rate. according to the speed changes of the traffic channel. In order to prove IMD to be most important variable in LNA we have tested IMD spurious in case that LNA always turns on and in case that LNA turns ON/OFF.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.175-177
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• 2006

According to the recommendation of International Maritime Organization, the Ministry Of Maritime Affairs and Fisheries (MOMAF) of Korea provides the real time Differential Global Positioning System service using maritime radio beacon from 1999. Due to the benefit of DGPS service, the need of this system is increased from various user groups for acquiring the better accuracy and integrity. Therefore, MOMAF has extended their service to inland by installing the additional 6 DGPS stations. This nationwide DGPS service will be fully deployed at 2007. In addition to the extension of service area, MOMAF has a plan to upgrade their nationwide DGPS to High Accuracy Nationwide DGPS (HANDGPS). The planned HANDGPS service of Korea will be a kind of long range RTK or Wide Area RTK techniques to provide under 1m accuracy and start their service from 2009 using the various broadcasting and communication media like as radio beacon, Wibro, Digital Multimedia Broadcasting, High Speed Packet Data Access. The introduction of nationwide DGPS system of Korea and its evolution plan will be addressed in this paper. The research activities related with HANDGPS in Korea is also presented.

• Journal of KIISE:Databases
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• v.32 no.6
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• pp.585-592
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• 2005

The Semantic Web is being studied as the next step in the evolution of the web. In the environment of the Semantic Web, the information must be understandable computers as well as a just human. So we use ontologies for describing the contents of the web resources. Among such ontologies, OWL is proposed as a recommendation by W3C. OWL data is represented as graph structure and the query is evaluated by traversing each node of the graph. In this paper, we propose the optimization technique based on signature to efficiently process the OWL data. Our approach minimizes traversing each node of the graph in query processing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.12
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• pp.1065-1075
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• 2012

For the purpose of providing high data rate real-time services, radio transmission technologies (RTT) for ship ad-hoc network (SANET) based on the Recommendation ITU-R 1842-1 are designed. Physical layer parameters of SANET are contrived to meet the requirements of the specification. In order to improve the link reliability for SANET, in this paper, we investigate the performance of the SANET with the multiple antennas, where receive combining (RC), transmit diversity (TD), and beamforming (BF) are employed, respectively. Based on the analysis of the packet error rate (PER) under the highly correlated maritime wireless channel model, we select the efficient multiple antenna schemes for SANET to improve the link reliability. In addition, the optimal MCS levels for the single-carrier (SC) SANET with the bandwidth of 25 kHz, and the multi-carrier (MC) SANET with the bandwidth of 50 kHz and 100 kHz are finalized.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.12
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• pp.923-927
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• 2009

The recent growth of a digital music market induces increasing demands for music searching and recommendation services. In order to improve the performance of music-based application services, the process of extracting melodies from polyphonic music is essential. In this paper, we propose a method to extract melodies from piano solo music which is highly polyphonic and has a wide pitch range. We categorize piano music into three classes taking into account the characteristics of music, and extract melodies according to each class. The performance evaluation for the implemented system showed that our method works successfully on a variety of piano solo music.

• Korean Journal of Oriental Medicine
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• v.17 no.2
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• pp.57-62
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• 2011

We in this paper propose a semantic search system using the basic ontology in Korean medicine field. The basic ontology provides a formalization of medicinal materials, formulas, and diseases of Korean medicine. Recently, many studies for the semantic search system have been proposed. However, they do not support the semantic search and reasoning in the domain of Korean medicine because they do not have the Korean medicine ontology. Our system provides the semantic search features of semantic keyword recommendation, associated information browsing, and ontology reasoning based on the basic ontology. In addition, they also have the features of ontology search of a form of table and graph, synonym search, and external Open API supports. The general search engines usually provide search results for the simple keyword, while our system can also provide the associated information with respect to search results by using ontology so that can recommend more exact results to users.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.11
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• pp.1116-1120
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• 2010

In this paper we present two refined neighbor selection algorithms for recommender systems and also show how the attributes of the items can be used for higher prediction quality. The refined neighbor selection algorithms adopt the transitivity-based neighbor selection method using virtual neighbors and alternate neighbors, respectively. The experimental results show that the recommender systems with the proposed algorithms outperform other systems and they can overcome the large scale dataset problem as well as the first rater problem without deteriorating prediction quality.