• Journal of Communications and Networks
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• v.16 no.6
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• pp.667-676
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• 2014

Connectivity is a crucial quality of service measure in wireless sensor networks. However, the network is always at risk of being split into several disconnected components owing to the sensor failures caused by various factors. To handle the connectivity problem, this paper introduces an in-advance mechanism to prevent network partitioning in the initial deployment phase. The approach is implemented in a distributed manner, and every node only needs to know local information of its 1-hop neighbors, which makes the approach scalable to large networks. The goal of the proposed mechanism is twofold. First, critical nodes are locally detected by the critical node detection (CND) algorithm based on the concept of maximal simplicial complex, and backups are arranged to tolerate their failures. Second, under a greedy rule, topological holes within the maximal simplicial complex as another potential risk to the network connectivity are patched step by step. Finally, we demonstrate the effectiveness of the proposed algorithm through simulation experiments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1662-1681
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• 2015

The efficient send and receive of information in VANET improves the efficiency of the safety and traffic services advertisment and discovery. However, if the V2V is the only communication system used, the restrictions of the urban environment and network drop the performance of VANET. In order to improve the performance of the network, it is necessary to use V2I communication as well as V2V communication. Therefore, RSUs must be placed in the environment. However due to the high costs of placement, the full coverage of the environment would not be possible. Therefore, it is necessary to optimally install a limited number of RSUs in the environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.5
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• pp.2453-2467
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• 2017

Wireless communication is a telecommunication technology, which enables wireless transmission between the portable devices to provide wireless access in all types of environments. In this research, the measurements and various empirical models are analysed and compared in order to find out a suitable propagation model to provide guidelines for cell planning of wireless communication systems. The measured data was taken in urban region with low vegetation and some trees at 900 MHz frequency band. Path loss models are useful planning tools, which permit the designers of cellular communication to obtain optimal levels for the base station deployment and meeting the expected service level requirements. Outcomes show that these empirical models tend to overestimate the propagation loss. As one of the key outputs, it was observed that the calculations of Weissberger model fit with the measured data in urban environment.

• Journal of Communications and Networks
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• v.4 no.4
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• pp.363-369
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• 2002

Towards the deployment of 3rd generation systems, Virtual Home Environment (VHE), stemming from 3GPP, appears to be a powerful concept advocating the provision and delivery of personalized services to roaming users across network and terminal boundaries. This paper aims to expose the pathway for materializing the VHE concept, via the specification, implementation and evaluation of a prototype. Core aspects for realizing the concept such as the business and roaming models are presented, while a VHE enabling architecture utilizing key technologies (OSA/Parlay, MExE, and USAT) is introduced. The proposed architecture has already been evaluated by performing an initial trial demonstration. Currently it is being extended to support VHE service provision to roaming users, an aspect to be addressed by the final trial.

• Journal of the Korea Safety Management & Science
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• v.2 no.3
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• pp.117-128
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• 2000

Initially, QFD (Quality Function Deployment) was introduced in 1972 to help design supertanker in Mitsubish's shipyards in Kob, Japan and formally defined by the American Supplier Institute in 1987 as a system for translating consumer requirements into appropriate company requirements at every stage, from research, through product design and development, to manufacture, distribution, installation, and marketing, sales and services. Although QFD has complex and tedious procedure to complete, since 1972, it has now been used by Japanese, American, and European because of its fruitful merits. The objective of this paper is to provide and analyze the trend on the choice of cultural subjects of university students using QFD. The data are collected by questionnaires. The samples for this study are randomly chosen from the universities in Seoul, Kangnung, and Samchok during 3 months (2000. 3 ∼ 2000. 5). The results of this study will play an important role not only for service of students but also for opening of subjects.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.1030-1037
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• 2002

통신서비스의 성패를 좌우하는 다양한 선택의 문제 중 하나는 신규 서비스를 제공하는 데 있어서, 어떤 기술을 도입하고 언제 상용화할 것인가를 결정하는 것이다 이러한 결정에는 서비스를 제공하는데 수반되는 투자와 비용, 시장 규모의 예측, 경쟁사업자 동향, 기존 또는 유사 기술과의 호환성이나 경쟁 관계 등이 고려되어야 하며, 이를 위해 다양한 경제성분석 방법이 활용되어 오고 있다. 그러나, 전통적인 현금흐름할인법의 경우, 현재 획득 가능하거나 추정할 수 있는 데이터를 이용해서 의사결정을 내리는 방식을 취하고 있으며 유연한 사고를 통해 수시로 변화하는 사업환경을 동태적 입장에서 의사결정을 지원할 수 없다는 한계를 지니고 있다. 최근, 이에 대한 대안으로 실물옵션이론을 활용한 경제성분석 방법이 소개되고 있다. 이는 금융옵션의 특성에 기반을 둔 방법으로, 주변 여건의 변화에 대해 유연한 의사결정을 지원할 수 있다는 측면이 통신서비스와 같은 불확실성이 큰 사업환경에 적합한 방법이 될 것으로 판단된다. 이에 본 논문에서는 새롭게 부각되고 있는 무선 LAN 서비스의 제공을 위한 통신 사업자의 서비스 도입 전략을 실물옵션이론을 활용해서 분석해 보고자 한다. 이를 통해, 통신사업자의 관점에서 무선 LAW 서비스의 제공을 추진할 때 가능성이 높은 몇 가지 시나리오에 대한 대응 방안과 유의점에 대해 고찰한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.386-388
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• 2017

TensorFlow와 알파고의 등장으로 인공지능의 높은 성능과 다양한 활용 가능성을 보이면서, 폭 넓은 산업 분야에서 머신러닝 기술에 대한 수요가 증가하고 있다. 반면, 머신러닝 기술은 GPU 기반 고속 병렬처리 기술과 인프라 기술을 기반으로 하고 있기 때문에, 머신러닝 기반 서비스 개발 및 제공에 어려움을 겪고 있다. 본 논문에서는 이와 같은 문제를 개선하기 위해서 개발한 고성능 GPU 기반 컨테이너 클라우드 시스템을 소개한다. 해당 시스템은 GPU 기반 고속 병렬처리를 지원하고, Kubernetes 클러스터에서 컨테이너를 기반으로 TensorFlow Serving을 손쉽게 배포할 수 있는 기능을 제공한다.

• ETRI Journal
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• v.19 no.3
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• pp.83-97
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• 1997

The CDMA Mobile System (CMS) has been developed by Electronics and Telecommunications Research Institute (ETRI) and field-tested for commercial service deployment in Korea. The project was started in 1989 and completed in 1995 with the CMS commercial test. During the course of development, there had been active technical cooperation with Qualcomm, Inc. and Korean manufacturers. The CMS adopted the basic CDMA concepts conforming to Korean CDMA system which was derived form IS-95. The CMS functions are allocated to subsystems by considering efficiency and expandability. The CMS consists of mobile stations and the infrastructure which is composed of base stations, mobile exchanges and home location register/authentication center. The commercial field tests performed both in Taejon and Seoul have indicated that the CMS capacity is 10 to 15 times larger than that of AMPS. This paper overviews the development history, system characteristics, architecture and test results.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.119-120
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• 2006

In this paper, we suggest postal RFID adaptation model, tag data structure and code which can be used for real time trace and track of parcel processing and pallet management. This paper also shows postal RFID application system architecture and testbed based on the proposed tag data structure and code, and shows recognition performance of tag on parcel and pallet by speed and mounting tag material such as can, water, and paper using implemented postal RFID system for postal logistics. The contribution of this paper is to stimulate deployment of RFID technology for postal logistics service and SCM (Supply Chain Management).

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.2 no.3
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• pp.48-60
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• 2003

With the rapid successful deployment of WLANs worldwide in numerous hotspots for high data rate, wireless access for data services has created the need to integrate the Cellular Networks with WLAN Networks. The integrated wireless environment will provide the end user a much better service experience along with a single subscription and a single bill. In this paper we focus on inter-working approaches, which combine WLANs and Cellular Networks into an integrated wireless environment capable of ubiquitous access to data services and very high data rates in hotspots areas. We first list the key requirements which are currently being standardized within the 30PP for integration with WLANs networks. We discuss two inter-working architectures namely loosely coupled and tightly coupled This paper will detail the loosely coupled inter-working approach while briefly discussing the tightly coupled inter-working. Finally, we will conclude that the loosely coupled approach is evolutionary and less intrusive than the tightly coupled approach.