• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.140-145
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• 2009

Recently, lots of research activities have been carried out to provide advanced smart control functions applying a computer networking technology to telemeter/telecontrol systems. In this paper, we suggest client/server architecture with specially designed remote and local control software for applicant those to greenhouse model. The server system collects and integrates various datas related sensor or actuator, and stores in database maintaining high quality of remote I/O control operation. Where as the client system simply operation such as control panel on the internet web browser. Implemented system well communicate interactively both monitoring and control status of greenhouse including multimedia informations. In this study we also analyze the extent of the performance enhancement in terms of overall throughput and data transfer time effected by packet size.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.109-112
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• 2017

WBAN (Wearable Body Area Network)는 옷이나 몸에 이식된 디바이스들이 몸을 중심으로 결합이나 통신하는 네트워크를 뜻한다. 여기서 사람이 몸에 착용하는 장치인 웨어러블 디바이스는 가벼운 형태의 배터리를 요구한다. 그로 인해, 다른 기기들과는 달리 짧은 배터리 수명을 가질 뿐만 아니라 통신에 관한 제약을 발생시킨다. 따라서 본 논문에서는 저전력 프로토콜을 지원하는 다중대역 웨어러블 디바이스 제어 시스템을 제안한다. 이를 위해 BLE (Bluetooth Low Energy) 기반의 프로토콜 스택으로 BLE, 6LoWPAN (IPv6 over Low power WPAN), CoAP (Constrained Application Protocol)을 적용해 데이터 패킷 크기를 감소 시키고 BLE/Wi-Fi 선택 기능을 통해 통신 제약을 완화하고 전체적인 WBAN 에서의 소비 전력을 감소하고자한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.5
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• pp.344-354
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• 2013

In this paper, In order to solve the traffic of the SNS to be executed on smartphone, we propose the design of the SNS integrated gateway server. Also, we capture the payload size in a variety of methods to send the MQTT protocol and QoS level of MQTT protocol for communication between the client and the Gateway. And we present the results and analysis of packet loss and end-to-end delay. By using analysis proposed, we present the results of the integrated SNS Gateway push notification protocol design.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.2027-2034
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• 1997

Frame relay is a fast packet switching technology that performs relaying and multiplexing frames with variable lengths over a wide area link at the T1 or E1 speed, by elminating error and flow control in the network. In frame relay networks, congestion control is typically performed through the rate enforcement with a discard eligibility (DE) bit, and the explicit negative feedback meachanisms using explicit congetion notification bits. In this paper, we consider the congestiong control scheme using the rate enforcement mechanism with DE bit for frame relay network. Assuming that each frame with exponentially distributed length arrives according to the Poission fashion, we can treat the frame relay switch as an M/M/1/K priority queueing system with pushout basis. We analyze and present the blocking probabilities and waiting time distributions of frames.

• Journal of the Korea Society of Computer and Information
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• v.15 no.8
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• pp.79-87
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• 2010

It is widely accepted that the coverage with high user densities in mobile multimedia environments can only be achieved with small cell such as micro- and pico-cell. If handover events occur during the transmission of multimedia, the efficient resource reservation and handover methods are necessary in order to maintain the same QoS of transmitted multimedia traffic because the QoS may be defected by some delay and information loss. In this paper, we propose a resource allocation method in the next generation mobile communication systems, in which the resource allocation process has a tight relation with call admission, call load, and packet scheduling. The simulation results show that our proposed method provides a excellent performance.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.1
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• pp.21-26
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• 2002

Video stream invoke a variety of traffic with the structure of compression algorithm and image complexity. Thus, it is difficult to allocate the resource on the both sides of sender and receiver, and playout on the Internet such as a packet switched network. Thus, in this paper we proposed video stream smoothing using multistream for the effective transmission of video stream. This method specifies the type of LDU(logical data unit) according to the type of original stream, and then makes a large number of streams as a fixed size, and transfers them. So, the proposed method can reduce the buffering time which occurs during the process of the smoothing and prefetch be robust to the jitter on network, as well. Consequently, it has the effective transmission characteristics of fully utilizing the clients bandwidth.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.9-12
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• 2000

In this paper, we carry out a performance study related to the Advanced Peer-to-Peer Network(APPN). For this particular network, it has been proposed to use the leaky bucket as a way of controlling congestion within the network. On the top of leaky bucket type rate based congestion control scheme for high speed networks, a user will typically operate an error control scheme for retransmitting lost and erroneous packets. We propose a Perform ance model in order to study the Interaction between a user's error control scheme and the leaky bucket congestion control scheme for high speed networks. Simulation results show that parameters such as the window size and the token generation rate in the leaky bucket are key factors affecting the end-to-end delay.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.111-114
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• 2006

This paper describes measurement of energy consumption when various size of data packets, on the both broadcast and point-to-point of Wireless network interface, are transmitted, received and discarded in the environment of Ad-hoc network. This experiment measures energy consumption using IEEE 802.11 wireless network interface with each condition. Since the measurements induces linear equation, it can provide useful information for protocol designer and developer. And this paper analyzes the information of behavior of energy consumption for the energy-aware design and the evaluation of network protocol on the practical wireless environment.

• Journal of the Korea Society for Simulation
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• v.27 no.4
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• pp.27-45
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• 2018

The terrestrial communication network and the underwater acoustic communication network have very different communication characteristics each other in operational environments, communication media, propagation delay, frequency bandwidth, transmission speed, bit error rate, and so on. These different characteristics cause some different address schemes and different maximum transmission units and, as a result, these differences must form certainly obstacles to the intercommunication between a terrestrial communication network and an underwater acoustic communication network. In this paper, we presents a method to use the virtual addresses to resolve the interconnection problem caused by different address schemes between a terrestrial communication network and an underwater acoustic communication network, and, through a mathematical modeling, we analyze the performance on the message transceiving delay time in the underwater environment.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.241-248
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• 2006

Mobile computing has such characteristics as portability, wireless network, mobility, etc. These characteristics cause various problems to mobile terminals like frequent disconnection, high error rate, and varying network status. These problems motivate us to develop an adaptive error control mechanism for supporting multimedia service in mobile computing environment. In this paper, we propose the Adaptive Error Control(AEC) scheme using client's buffer size and current error rate. After categorizing the status into four groups according to client's buffer size and current error rate, this scheme applies an appropriate error control scheme to each status. In this scheme, thresholds of buffer size and error rate are determined by the data transmission time, play rate and average VOP size, and by the probability of error for a sequence of packets. The performance of proposed scheme is evaluated by flaying MPEG-4 files on an experimental client/server environment, respectively. The results show that error correcting rate is similar to other schemes while the time for correcting error reduce a little. In addition, the size of data for correcting error is decreased by 23% compared with FEC and Hybrid FEC, respectively. Theses results demonstrate that the proposed scheme is more suitable in mobile computing environment with small bandwidth and varying environment than existing schemes.