• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.11a
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• pp.309-312
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• 1998

대용량 통신처리시스템은 전화망 및 ISDN 가입자에게 패킷망, 인터넷을 통해 PC 통신 서비스나 인터넷 서비스를 제공하는 것을 목적으로 하는 정보 서비스 게이트웨이 장치이다. 각종 망의 인터페이스를 담당하는 망 정합장치들은 대용량 통신처리시스템내의 내부 전달망을 통하여 연동하는 구조를 가지며, 망 정합장치들간의 연결을 통해 정보 제공 서비스 및 과금 회수 대행 등의 관리 서비스들이 이루어진다. 따라서, 이들 망 정합장치간의 신뢰성 있는 데이터 전달을 보장하기 위해서 두 장치간에 연결형 데이터 링크의 설정이 요구된다. 본 논문에서는 이러한 이종망 상에서의 통신처리 노드간 링크 제어 프로토콜을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.137-138
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• 2012

최근 다양한 센서를 활용한 보안 감시 시스템의 수요가 증가하면서 센서 데이터의 효율적인 관리 또한 중요해지고 있다. 본 논문에서는 높은 확장성 대비 낮은 비용이 장점인 클라우드 환경을 적용한 센서 클라우드 시스템을 설계한다. 본 시스템에서는 옥내에 분산되어 있는 센서 네트워크가 침입자를 감지하여 클라우드 게이트웨이를 통해 센서 클라우드로 센서 데이터를 전달한다. 전달된 센서 데이터는 Apache Hadoop 을 기반으로 하는 데이터 서버에 분산 저장된다. 또한 본 시스템은 센서 데이터를 실시간으로 파악하기 위한 시스템 인터페이스를 포함한다.

• Journal of Internet Computing and Services
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• v.22 no.6
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• pp.129-140
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• 2021

The next generation mBcN should be built to cooperate with the wireless network to support hyper-speed and hyper-connectivity. In this paper, we propose a network architecture for the cooperation mBcN and 5G commercial network and architecture of the cooperative security gateway required for the cooperation. The proposed cooperative security gateway is between gNB and UPF to support LBO, SFC, and security. Our analysis shows that the proposed architecture has several advantages. First of all, user equipment connected with the mBcN can be easily connected through the 5G commercial radio network to the mBcN. Second, the military application traffic can be transmitted to mBcN without going through the 5G core network, reducing the end-to-end transmission delay without causing the traffic load on the 5G core network. In addition, the security level of the military application can effectively be maintained because the user equipment can be connected to the cooperative security gateway, and the traffic generated by the user equipment is transmitted to the mBcN without going through the 5G core network. Finally, we demonstrate that LBO, SFC, and security modules are essential functions of the proposed gateway in the 5G test-bed environment.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.5
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• pp.286-299
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• 2006

Due to the continuing technical progress in the capabilities of modeling, simulation, and sensor devices, huge volume data with very high resolution are common. In scientific visualization, various interactive real-time techniques on high performance parallel computers to effectively render such large scale volume data sets have been proposed. In this paper, we present a mobile volume visualization system that consists of mobile clients, gateways, and parallel rendering servers. The mobile clients allow to explore the regions of interests adaptively in higher resolution level as well as specify rendering / viewing parameters interactively which are sent to parallel rendering server. The gateways play a role in managing requests / responses between mobile clients and parallel rendering servers for stable services. The parallel rendering servers visualize the specified sub-volume with rendering contexts from clients and then transfer the high quality final images back. This proposed system lets multi-users with PDA simultaneously share commonly interesting parts of huge volume, rendering contexts, and final images through CSCW(Computer Supported Cooperative Work) mode.

• Journal of IKEEE
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• v.2 no.1 s.2
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• pp.15-23
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• 1998

In this paper, distributed mixer is studied at microwave frequency. The circuit of distributed mixer composed of gate 1,2, drain transmission lines, matching circuits in input and output terminal, DGFET's. For impedance matching of input and output port at higher frequency, image impedance concept is introduced. In distributed mixer, a DGFET's impedances are absorbed by artificial transmission line, this type of mixer can get a very broadband characteristics compared to that of current systems. A RF/LO signal is applied to each gate input port, and are excited the drain transmission line through transcondutance of the DGFET's. The output signals from each drain port of DGFET's added in same phases. We designed and frabricated the distributed mixer, and a conversion gain, noise figure, bandwidth, LO/RF isolation of the mixer are shown through computer simulation and experimentation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.786-791
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• 2021

In this paper, in order to minimize limitations such as signal interference and positioning errors in existing indoor positioning systems, a smart LED-based positioning system for excellent line-of-sight radio environments and precise location tracking is proposed to improve accuracy. An IEEE 802.4 Zigbee module is mounted on the SMPS board of a smart LED; RSSI and LQI signals are received from a moving tag, and the system is configured to transmit the measured data to the positioning server through a gateway. For the experiment, the necessary hardware, such as the gateway and the smart LED module, were separately designed, and the experiment was conducted after configuring the system in an external field office. The positioning error was within 70cm as a result of performing complex calculations in the positioning server after transmitting a vector value of the moving object obtained from the direction sensor, together with a signal from the moving object received by the smart LED. The result is a significantly improved positioning error, compared to an existing short-range wireless communications-based system, and shows the level at which commercial products can be implemented.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.31-40
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• 2016

In vehicular ad-hoc networks (VANETs), vehicles sense information on emergency incidents (e.g., accidents, unexpected road conditions, etc.) and propagate this information to following vehicles and a server to share the information. However, this process of emergency message propagation is based on multiple broadcast messages and can lead to broadcast storms. To address this issue, in this work, we use a novel approach to detect the vehicles that are farthest away but within communication range of the transmitting vehicle. Specifically, we discuss a signal-to-noise ratio (SNR)-based linear back-off (SLB) scheme where vehicles implicitly detect their relative locations to the transmitter with respect to the SNR of the received packets. Once the relative locations are detected, nodes that are farther away will set a relatively shorter back-off to prioritize its forwarding process so that other vehicles can suppress their transmissions based on packet overhearing. We evaluate SLB using a realistic simulation environment which consists of a NS-3 VANET simulation environment, a software-based WiFi-IP gateway, and an ITS server operating on a separate machine. Comparisons with other broadcasting-based schemes indicate that SLB successfully propagates emergency messages with latencies and hop counts that is close to the experimental optimal while reducing the number of transmissions by as much as 1/20.

• 전자공학회논문지 IE
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• v.44 no.2
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• pp.14-20
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• 2007

This paper presents quaternary D flip-flop with advanced performance. Quaternary D flip-flop is composed of the components such as thermometer code output circuit, EX-OR gate, bias inverter, transmission gate and binary D flip-flop circuit. The designed circuit is simulated by HSPICE in $0.35{\mu}m$ one-poly six-metal CMOS process parameters with a single +3.3V supply voltage. In the simulations, sampling frequencies is measured around 100MHz. The PDP parameters and FOM we estimated to be 59.3fJ, 33.7 respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.447-447
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• 2013

최근 전자산업의 발전으로 차세대 디스플레이 소자로 산화물반도체가 주목받고 있다. 산화물 반도체는 저온공정, 높은 이동도 및 투과율을 가지기 때문에 이러한 공정이나 물성 측면에 있어 기존의 a-Si, LTPS 등을 대채할 만한 소자로서 연구가 활발이 이루어지고 있다. 특히 고해상도 및 고속구동이 진행됨에 따라 높은 이동도의 필요성이 대두되고 있다. 본 연구에서는 IGZO 산화물 반도체 박막트랜지스터의 이동도 개선을 위해 나노입자를 사용하였다. 게이트전극으로 사용된 Heaviliy doped P-type Si 기판위에 200 nm의 SiO2 절연층을 성장시킨 후, 채널로 작동하기 위한 IGZO 박막을 증착하기 전에 10~20 nm 크기의 니켈, 금 나노입자를 부착시켰다. 열처리 온도는 $350^{\circ}C$, 90분동안 진행하였고, 100 nm의 알루미늄 전극을 증착시켜 TFT 소자를 제작하였다. TFT 소자가 동작할 시, IGZO 박막 내부의 전자들은 게이트 전압으로 인해 하부로 이동하여 채널을 형성, 동시에 드레인 전압으로 인한 캐리어들의 움직임으로 인해 소자가 동작하게 된다. 본 연구에서는 채널이 형성되는 계면 부근에 전도성이 높은 금속 나노입자를 부착시켜 다수 캐리어인 전자가 채널을 통과할 때 전류흐름에 금속 나노입자들이 기여하여 전기적 특성의 변화에 어떠한 영향을 주는지 연구하였다. 반응시간을 조절하여 기판에 붙는 나노입자의 밀도 변화에 따른 특성과 다양한 크기(5, 10, 20 nm)를 갖는 금, 니켈 나노입자를 포함한 IGZO TFTs 소자를 제작하여 전달특성, 출력특성의 변화를 비교하였고, 실질적인 채널길이의 감소효율과 캐리어 이동도의 변화를 비교분석 하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.445-450
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• 2011

In this paper, we describe the implementation of an wireless sensor network testbed. We developed a web-based sensor network gateway and enhanced the Surge program which is used for sending and routing of packets in the sensor field. The developed program can transmit the source data of sensor nodes to the sink node via multi-hop routing, and deliver user commands to actuate sensor related equipments. Moreover, in this testbed, the data transport path from a node to the sink can be monitored. Thus we can approximate the network topology and the relative positions of sensor nodes. We also describe an application of the testbed that is used for controlling a remote robot.