• ETRI Journal
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• v.44 no.6
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• pp.915-924
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• 2022

In this paper, we present a two-stage scalable channel estimator (TSCE), a deep learning (DL)-based scalable, and robust channel estimator for wireless cellular networks, which is made up of two DL networks to efficiently support different resource allocation sizes and reference signal configurations. Both networks use the transformer, one of cutting-edge neural network architecture, as a backbone for accurate estimation. For computation-efficient global feature extractions, we propose using window and window averaging-based self-attentions. Our results show that TSCE learns wireless propagation channels correctly and outperforms both traditional estimators and baseline DL-based estimators. Additionally, scalability and robustness evaluations are performed, revealing that TSCE is more robust in various environments than the baseline DL-based estimators.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.628-628
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• 2006

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1993.04a
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• pp.457-458
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• 1993

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1993.04a
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• pp.455-456
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• 1993

• Journal of the Korean Society for information Management
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• v.31 no.3
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• pp.153-179
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• 2014

This study explores the characteristics of centrality measures for analyzing researchers' impact and structural positions in research collaboration networks. We investigate four binary network centrality measures (degree centrality, closeness centrality, betweenness centrality, and PageRank), and seven existing weighted network centrality measures (triangle betweenness centrality, mean association, weighted PageRank, collaboration h-index, collaboration hs-index, complex degree centrality, and c-index) for research collaboration networks. And we propose SSR, which is a new weighted centrality measure for collaboration networks. Using research collaboration data from three different research domains including architecture, library and information science, and marketing, the above twelve centrality measures are calculated and compared each other. Results indicate that the weighted network centrality measures are needed to consider collaboration strength as well as collaboration range in research collaboration networks. We also recommend that when considering both collaboration strength and range, it is appropriate to apply triangle betweenness centrality and SSR to investigate global centrality and local centrality in collaboration networks.

• ETRI Journal
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• v.30 no.5
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• pp.696-706
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• 2008

With the increasing need for intelligent environment monitoring applications and the decreasing cost of manufacturing sensor devices, it is likely that a wide variety of sensor networks will be deployed in the near future. In this environment, the way to access heterogeneous sensor networks and the way to integrate various sensor data are very important. This paper proposes the common system for middleware of sensor networks (COSMOS), which provides integrated data processing over multiple heterogeneous sensor networks based on sensor network abstraction called the sensor network common interface. Specifically, this paper introduces the sensor network common interface which defines a standardized communication protocol and message formats used between the COSMOS and sensor networks.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.101-104
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• 2007

Efficient Query processing and optimization are critical for reducing network traffic and decreasing latency of query when accessing and manipulating sensor data of large-scale sensor networks. Currently it has been studied in sensor database projects. These works have mainly focused on in-network query processing for sensor networks and assumes homogeneous sensor networks, where each sensor network has same hardware and software configuration. In this paper, we present a framework for efficient query processing over heterogeneous sensor networks. Our proposed framework introduces query processing paradigm considering two heterogeneous characteristics of sensor networks: (1) data dissemination approach such as push, pull, and hybrid; (2) query processing capability of sensor networks if they may support in-network aggregation, spatial, periodic and conditional operators. Additionally, we propose multi-query optimization strategies supporting cross-translation between data acquisition query and data stream query to minimize total cost of multiple queries. It has been implemented in WSN middleware, COSMOS, developed by ETRI.

• Journal of the Korean Society for information Management
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• v.7 no.1
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• pp.96-120
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• 1990

Academic and research computer networks are the essential communications component that can provide scientists and engineers with convenient access to local and remote computing and information resources. Nowadays, academic and research computer networks, providing access to a variety of resources and information services, can significantly increase the productivity of scientists and engineers. In Korea there have been some activities of academic and research networks since early of 1980. This study presents background of development of computer network, summaries the types of services offered by academic and research computer networks and analyses the potential benefits resulting from their availability. Use and need of Korean researchers about academic and research computer networks are also reviewed as well as it prospects Korean Computer Network for Education and Research & Development, a new national-base network being implemented by government.

• Journal of Information Processing Systems
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• v.1 no.1 s.1
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• pp.49-54
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• 2005

With the recent advances in Micro Electro Mechanical System (MEMS) technology, low cost and low power consumption wireless micro sensor nodes have become available. However, energy-efficient routing is one of the most important key technologies in wireless sensor networks as sensor nodes are highly energy-constrained. Therefore, many researchers have proposed routing protocols for sensor networks, especially cluster-based routing protocols, which have many advantages such as reduced control messages, bandwidth re-usability, and improved power control. Some protocols use information on the locations of sensor nodes to construct clusters efficiently. However, it is rare that all sensor nodes know their positions. In this article, we propose another cluster-based routing protocol for sensor networks. This protocol does not use information concerning the locations of sensor nodes, but uses the remaining energy of sensor networks and the desirable number of cluster heads according to the circumstances of the sensor networks. From performance simulation, we found that the proposed protocol shows better performance than the low-energy adaptive clustering hierarchy (LEACH).

• Knowledge Management Research
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• v.12 no.4
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• pp.17-40
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• 2011

This study examines the differences of enacting models and influential causes of benefit-sharing practices between Korean automobile networks and the Japanese networks. The case study method is chosen for this research because only small numbers of supply networks adopt benefit-sharing practices. I employ semi-structured interviews with managers from four automobile manufacturers and eight of their suppliers in South Korea and Japan. I find that Japanese automobile networks have adopted a higher level of trust-demanding, with a higher level of value-creating models such as supplier development, joint-new-product development. Whereas, the Korean networks have adopted the lower trust demanding, also less profitable models such as supplier's suggestion and buyer's suggestion. In terms of work-related cultural values, I find that Japanese networks emphasized collectivism. Both buyers and suppliers in the Japanese networks are supposed to have common causes. In contrast, Korean networks emphasized individualism. Both buyers and suppliers of Korea generally do not identify that they are common group members with a common cause. I also find that a slight differences of the enacting models and the causes between foreign-owned networks and domestic-owned networks within each country. Foreign-owned networks have adopted lower trust demanding, also less profitable models. The findings demonstrate that the cultural values have a decisive influence on the adoption of benefit sharing models for the networks in Japan, and South Korea.