• The Transactions of the Korea Information Processing Society
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• v.6 no.11S
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• pp.3390-3398
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• 1999

To achieve high-speed communication and to improve QoS characteristics, ATM is now being used as underlying transfer mechanism of Internet protocols, or TCP/IP. When TCP uses the ABR service in ATM networks, the ABR service control is important to improve the performance of TCP/IP traffic as long as there is no interaction between ABR rate control and TCP flow control. In such environment, the interoperability of EFCI and ER switches becomes unavoidable in order to more effectively control ABR traffic in ATM network. In this paper, we use the model of mixed EFCI-ER environment and discuss the performance issues, e.g., the fairness of bandwidth allocation, drop rate, throughput by using various ER switch algorithms. Among various ERSwitch algorithms, we present one algorithm that have a less network topology and allocate the fair share of VC bandwidth by simulation results.

• The Transactions of the Korea Information Processing Society
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• v.7 no.6
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• pp.1941-1948
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• 2000

Multistage interconnection networks (MINs) have been recognized as an efficient interconnection network for high-performance computer systems and also have been recently identified to be effective for a switching fabric of new communication structures - gigabit ethernet switch, terabit router, and ATM (asynchronous transfer mode). While lots of models analyzing the performance of MINs have been proposed, they are either inaccurate or, even if accurate, very complex for the analysis. In this paper, we propose an extremely simple mode for evaluating the multibuffered MIN with small clock cycles based on the approximation approach. Comprehensive computer simulation shows that the proposed model is very accurate in terms of the throughput and mean delay. Furthermore, it significantly reduces the computing overhead due to its simplicity.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.105-107
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• 2000

유무선 고속 네트워크 기술을 통합한 새로운 컴퓨팅 환경을 이동 컴퓨팅이라 한다. 이동 사용자는 고속 네트워크 상에서 다양한 종류의 서비스를 액세스할 수 있을 것이다. 고속 네트워크에서 그러한 서비스들의 품질은 다수의 QoS 매개변수로 상세될 수 있다. 이동환경에서 가장 중요한 QoS 매개변수는 이동 사용자에게 단절 자유 서비스를 제공하는 무단절 통신의 보장이다. 서비스 단절은 활동적인 핸드오프에 의해 발생된다. 본 논문에서는 단절 자유 서비스에 대한 언어 QoS 보장을 제공하는 퍼지 무단절 통신 방법에서 무단절 정도와 이동 단말의 속도, 이동 편차, 셀의 직경에 따라 제공되는 무단절 서비스 확률의 정도를 평가한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.535-537
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• 2004

최근 센서 네트워크에 대한 필요성이 증대되면서 센서 기술과 통신 기술 등 센서 네트워크의 기반기술에 대한 연구가 활발하게 진행되고 있다. 특히, 센서 네트워크에서 센서 노드의 수명은 센서의 배터리 전력량에 비례하므로 보다 적은 전력으로 통신을 수행하는 기술들에 관심이 집중되고 있다. 이러한 저전력 통신 프로토콜 가운데 대표적인 것이 시간 분할 다중 접속(TDMA) 기반 MAC 프로토콜이다. 지정된 시간에만 센서 노드의 통신 상태를 정지(sleep)상태에서 유휴(idle)상태로 변경하여 통신을 수행하므로 전력 소비를 최소화시키는 기술이다. 그러나 이웃한 다른 센서들 간의 통신을 간섭하지 않기 위해 센서들은 통신시 서로 다른 주파수를 사용해야 한다. 이러한 제한 사항을 충족시키기 위해서는 센서 노드들이 다양한 주파수를 청취할 수 있어야 하며. 이는 센서 노드 생산시 제조단가의 증가와 직결되어 센서 네트워크의 상용화에 주요한 문제가 될 수 있다. 따라서 본 논문에서는 시간 분할접속(TDMA) 기반 저전력 MAC 프로토콜에서 단일 주파수를 사용한 수 있도록 통신 시간(time slot)을 할당하는 알고리즘을 제안하고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.313-315
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• 2003

멀티캐스트 기술은 인터넷 서비스에 필수불가결한 요소임에도 불구하고, 네트워크상의 구현에 어려움으로 인해 그 기술이 활용되지 못하고 있다. 멀티캐스트 기술의 장점을 활용하기 위하여 어플리케이션 레벨에서 멀티캐스트 기능을 구현한 응용 멀티캐스트 프로토콜들이 제안되고 있다[1,2]. 본 논문에서는 이기종 환경에서 다수의 송신자가 상이한 전송률을 갖는 수신자들에게 다양한 대역폭을 제공하고 보다 효과적인 실시간 스트리밍 전송 서비스를 지원하기 위한 멀티캐스트 기법을 제안한다. 본 연구에서 제안하는 멀티캐스트 기법의 통시구조는 소스기반의 전송트리가 내포되어 있는 n차 정다면체 구조를 갖으며, 서로 비슷한 전송률을 갖는 수신자들끼리 서브 그룹을 구성하므로 실시간 데이터 전송시 주어진 대역폭을 효과적으로 사용할 수 있다.

• Clinical and Experimental Pediatrics
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• v.61 no.1
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• pp.1-5
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• 2018

We often overlook the importance of several safety issues such as identification of patients, timeout procedure, hand hygiene, handoff communication, and many others. This ignorance, along with many other issues, leads to medical error being ranked as a third leading cause of death in the U.S. Consequently, quality improvement (QI) has become one of the major subjects in healthcare despite a relatively short history. Improving quality is about making healthcare safe, effective, patient-centered, timely, efficient, and equitable. Understanding the need and methodology of QI as well as participation is now essential for physicians. Although basic QI methodology has not changed, one of the most fascinating changes in recent QI is conducting large-scale QI projects through multicenter networks. Prospective multicenter QI projects utilizing the Korean Neonatal Network are a substantial initiation of pediatric QI in Korea. The Korean Pediatric Society should set ambitious goals for QI activities for every primary care pediatrician and pediatric subspecialist.

• IE interfaces
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• v.17 no.1
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• pp.121-127
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• 2004

In this paper, we present the base station(BS) processing capacity to provide the multimedia services in IMT-2000 wireless communication network. The IMT-2000 services are classified into two types, circuit and packet services, and user‘s environments such as indoor, pedestrian and vehicle are considered. Using the parameters of service economics and wireless technology, the user's reference traffic and BS‘s traffic are computed. The traffic is measured by throughput(kbps). Based on the measured traffic, the accommodating users in BS are also evaluated. In addition to, the BS design capacity is presented for varying the number of users and traffic distribution in different user's environments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.894-897
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• 1995

This paper focuses on self-organization of fuzzy rules for performance management of computer communication networks serving manufacturing systems. The performance management aims to improve the network performance in handling various types of messages by on-line adjustment of protocol parameters. The principle of fuzzy logic has been used in representing the knowledge of human expert on the performance management and in deriving management decisions. In this paper, we present applications of genetic algorithm, simulated annealing, and evolution strategies to find a better set of rules for various network conditions. The efficacy of this self-organization is demonstrated by discrete simulation of an IEEE 802.4 network.

• Journal of Sensor Science and Technology
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• v.23 no.5
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• pp.349-355
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• 2014

In this paper, we developed a new method to transmit multiple visible light channels in time division mode using the AC power line frequency in order to prevent the crosstalk between adjacent optical signals. Synchronizing pulses are generated from the 220 V power line, and one pulse period is subdivided into several time slots for visible light channels. Each channel transmits data in a predefined time slot without interfering adjacent channels. In experiments, synchronizing pulses with a repetition rate of 240 Hz were generated from the 60 Hz power line, and three VLC channels with a bit rate of 9.6 kbps transmitted data independently using the time slots between synchronizing pulses. This configuration is very useful in constructing time division VLC networks for multiple sensors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.799-808
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• 2007

BACnet is an international standard communication protocol especially designed for building automation and control systems. BACnet uses the Master-Slave/Token-Passing (MS/TP) protocol as one of its field-level networks. A BACnet MS/TP field controller prototype and MS/TP network monitoring system are developed in this study. This report introduces the design and implementation methodology of a BACnet MS/TP field controller hardware, firmware and protocol stack. This report also presents the implementation methodology of BACnet MS/TP network monitoring system using VTS (Visual Test Shell). The methodologies introduced in this report will facilitate the develop and implementation of the BACnet-based control systems in building automation area.