• 전자공학회논문지T
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• 제36T권2호
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• pp.14-20
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• 1999

본 논문에서는 자율분산로봇의 무선 통신시스템에 관하여 연구하였다. 이동로봇 사이의 협조 동작을 위하여 통신의 구현이 필요하다. 따라서, 우리는 이동로봇에 무선통신시스템을 적용하여 실험하였다. 그리고, 여러 이동로봇 사이의 상호작용을 연구하기 위하여 분산된 제어구조의 개념과 실험적 구조를 설명한다.

• 대한산업공학회지
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• 제32권2호
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• pp.120-125
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• 2006

Since Korean government has implemented the "Number Portability System" in the domestic mobile communications market, mobile communication companies have been striving to hold onto existing customers and at the same time to attract new customers. This paper presents a competing risk model that considers the characteristics of a customer in order to predict the customer's life under the "Number Portability System." Three competing risks considered are pricing policy, quality of communication, and usefulness of service. It was observed that the customers who pay more are less sensitive on pricing policy younger people are less sensitive than older people to the quality of communication and women are more sensitive than men to the degree of usefulness of service. We expect that the result of this study can be used as a guideline for effective management of mobile phone customers under the Number Portability System.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.81-82
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• 2006

Most work on cooperative diversity has assumed that the cooperating group (source and partners) and the associated average channel conditions between terminals (source, partners, and destination) are predetermined. In practical situations, however, it is important to develop the efficient algorithms for assigning the terminals with good inter-user channels for cooperating groups. In this paper, we propose the partner assignment algorithm for cooperative diversity in mobile communication systems. The proposed partner assignment algorithm is investigated by using the path loss model for mobile communication systems. Numerical results show that the proposed partner assignment algorithm provides the comparable probability of cooperative transmission to the partner assignment algorithm using exhaustive search. The probability of cooperative transmission increases with the number of users, which gives potential benefits of practical implementation to user cooperation in mobile communication systems.

• Journal of Communications and Networks
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• 제13권1호
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• pp.56-62
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• 2011

In this paper, we propose a block-based selective orthogonal frequency division multiplexing (OFDM) decode-and-forward relaying scheme for 4G mobile communication systems. In the scheme, an OFDM symbol is divided into blocks and one relay is selected for each block. Theoretical outage performance and error performance are analyzed and evaluated. A unified outage expression is given for our scheme and the other two schemes and the lower bound of the bit error rate of the three schemes is also obtained. The effect of the coherence bandwidth on the proposed scheme is also investigated. Monte Carlo simulations are carried out to validate our analysis. The scheme can obtain a good tradeoff between complexity and performance and can be used in future 4G mobile communication systems.

• 한국전자통신학회논문지
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• 제7권1호
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• pp.187-194
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• 2012

본 논문에서는 이동 로봇이 자율주행을 하기 위해 사용되는 충돌회피 알고리즘을 실제 로봇과 똑같은 환경에 적용된 시뮬레이터를 통해 성능을 알아본다. 이동 로봇의 충돌회피를 위해 기존에 인공전위계 알고리즘과 Elastic force 알고리즘 등이 제안되어져있다. 본 연구에서는 시뮬레이션을 통해 이 두 가지 방법에 의한 동작시간과 경로의 이동 길이를 비교하였다. 시뮬레이터는 IPC(Inter Process Communication)를 기반으로 개발되어졌으며, 알고리즘의 비교에는 차륜형 이동 로봇을 사용하였다.

• ETRI Journal
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• 제44권6호
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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.

• 대한의용생체공학회:의공학회지
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• 제26권2호
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• pp.65-71
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• 2005

The main obstacles for adopting a mobile health information system to existing hospital information system are the redundancy of clinical data and the additional workload for implementing the new system. To obtain a seamless communication and to reduce the workload of implementation, an easy and simple implementation strategy is required. We propose a mobile clinical information system (MobileMed) which is specially designed for the easy implementation. The key elements of MobileMed are a smart interface, an HL7 message server, a central clinical database (CCDB), and a web server. The smart interface module transfers the key information to the HL7 message server as new clinical tests data is recorded in the existing laboratory information system. The HL7 message server generates the HL7 messages and sends them to the CCDS. As a central database the CCDS collects the HL7 messages and presents them to the various mobile devices such as PDA. Through this study we might conclude that the architecture for the mobile system will be efficient for real-time data communication, and the specially designed interface will be an easy tool for implementing the mobile clinical information system.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 춘계종합학술대회
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• pp.495-498
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• 2007

최근, RFID 태그와 리더가 장착되고 무선 인터넷이 결합된 휴대전화로 이동통신 인프라를 이용하여 일상생활에 필요한 정보를 얻고 다양한 응용서비스를 이용할 수 있는 모바일 RFID 서비스의 상용화가 눈앞으로 다가오고 있다. 하지만 모바일 RFID 서비스로 인한 새로운 수익이 창출될 것으로 기대되고 있으나 관련 통신업체의 대규모 투자를 이끌어 내기 위해서는 모바일 RFID 서비스 수요에 대한 정확한 예측이 필요하다. 이에 본 논문은 모바일 RFID 서비스 수요예측을 통해 관련 통신업체의 투자를 확대할 수 있는 기반을 마련하고자 하였으며, 특히 다양한 모바일 RFID 서비스 모델의 유형에 따라 서비스 수요를 예측함을 통해 관련 통신업체의 서비스 투자 방향에 대한 의사결정에 도움이 되고자 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권3호
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• pp.815-834
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• 2012

Recently, along with the innovative development of wireless communication techniques and mobile devices, mobile P2P services in mobile wireless networks have gained a lot of attention. In this paper, we propose a resource discovery scheme with data dissemination over mobile P2P networks. In the proposed scheme, each peer manages a local information table, a resource index table, and a routing table in a local database to enhance the accuracy and cost of resource discovery. The local information table stores the status of a mobile peer, and the resource index table stores the resource information of the neighbor peers via the ranking function. The routing table is used to communicate with the neighbor peers. We use a timestamp message to determine whether or not the resource index table will be changed before the resource information is exchanged. Our ranking function considers the interest and mobility of the mobile peer and prioritizes the resource information transmitted from the neighbor peers. It is shown via various experiments that the proposed scheme outperforms the existing scheme.

• 한국전자통신학회논문지
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• 제14권1호
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• pp.205-212
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• 2019

모바일 폰의 급속한 확산으로 사용자들은 모바일 폰을 지속적으로 개인 활동에 연관시켜 활용하기 위해 많은 관심을 가지고 있다. 그리고 사용자들은 모바일 환경에서 더 쉽고, 간단하게 데이터를 공유(전송 및 수신), 저장하려는 요구가 증가하고 있다. 본 논문은 GCM 서비스를 기반으로 위치기반 서비스를 이용하여 일정한 거리에 위치한 다수의 사람들과 개인 정보 공유를 위해 모바일 폰의 모션 인식을 제안한다. 제안된 애플리케이션은 Android 운영 체제에서 실행되는 모바일 애플리케이션과 비동기적으로 통신할 수 있게 해주는 Google 클라우드 메시징을 기반으로 한다. 어디서나 모든 모바일 장치를 통해 개인 정보 공유를 쉽고, 간단하게, 실시간으로 액세스할 수 있으므로 경량 메커니즘의 요구 사항을 충족할 수 있다.