Tae-Gyu Kang

SIP/SDP signaling of media gateway with transcoding function in converged network

There has been changed network environment from PSTN only to several networks with versatile terminal. Transcodec comes out new issue for communication each other with different codecs in converged network. We classify call setup methods without transcodec and with trnscodec and. four kind positioning of transcoding function among network resources; IP terminal, conference bridge, third party transcoding server, and media server. We designed the SIP/SDP signaling of media gateway with transcoding function in converged network. SIP/SDP call signaling for media server proposed in this paper needs less message between nodes than one of conference bridge and third party transcoding server.

Reliable Transmission for Remote Device Management (RDM) Protocol in Lighting Control Networks

The Remote Device Management (RDM) protocol is used to manage lighting devices in the lighting control network. RDM provides bi-directional communication between lighting devices based on the modified DMX512 data link so as to perform device discovery, configuration, monitoring, and management of the devices connected through the DMX512 network. However, the RDM protocol does not provide a reliable packet transmission. To overcome this limitation, we propose the two retransmission schemes: sequence-based retransmission, and timer-based retransmission. In the existing RDM protocol, each response packet uses the same Transaction Number (TN) with that of the request packet from the controller. In the proposed schemes, we use TN to identify a lost or error message. For example, if a response packet with a specific TN number does not arrive within a pre-specified time, the controller will retransmit the concerned request message. From the numerical analysis, it is shown that the proposed retransmission schemes can give better reliability than the existing RDM protocol, and the sequence-based and timer-based retransmission schemes provide the different performance, depending on network environments.

Lighting-Aware and COntrol (LACO) Based on Bidirectional Networks

This paper presents the sensor dongle, or Lighting-Aware and COntrol (LACO), and its application software. LACO is implemented with optical sensors combined with VLC receiver to get the positioning-ID from illumination. Moreover, four bidirectional networks capable of interaction with LACO are classified and future trends of lighting system are also introduced.

Autonomous Lighting Control Based on Adjustable Illumination Model

Autonomous lighting control systems require a numerical illumination model in which the light level output in a room can be expected according to given dimming control inputs. Stationary illumination models, such as the zonal cavity method and the point by point method, might be difficult to adjust the model to on-site environments in which are suffused with various shading artifacts unconsidered in a preceding simulation stage. Thus, this paper suggests an adjustable illumination model through Neural Network which can fit the model to the environments by a learning technology. Secondly, the autonomous lighting control can be realized by using the inverse of the illumination model. A small-sized replica of an actual lighting space is used for evaluation of our approach.

TAC Reconfiguration for Paging Optimization in LTE-Based Mobile Communication Systems

In LTE-based mobile communication systems, a Tracking Area Code (TAC) is defined by a group of cells for paging operation. The existing TAC configuration has been made manually by considering only the geographical location of cells, and thus it tends to induce an imbalanced TAC configuration and a low paging success rate. In this paper, we propose a reconfiguration of the existing TAC configurations to get a more balanced TAC configuration and to increase the paging success rate. The proposed TAC reconfiguration scheme is designed by considering the mobility (handover) ratio of mobile users between cells as well as the number of users in cells. From the performance analysis with real traffic data of SK Telecom in Korea, we see that the proposed scheme can provide more balanced TAC configurations and also improve the paging success rates by 8%, compared to the existing TAC configurations.

Design of electronic commerce workflow model adapted to restructuring value chain for trading costs saving

This paper introduces an approach dealing with restructuring value chains due to the advent of electronic commerce. The approach is based upon workflow technology enabling flow of data and control over cross-organizations. In order to describe the procedure of a restructured value chain that processes inter-organization transactions, we used a virtual value chain model having four nodes, such as consumer, merchant, delivery, and manufactory, that are logically hooked on the Internet. We have strong belief that the workflow technology merged into the electronic commerce will be effective in terms of restructuring market value chains and reducing costs of processing cross-organizational transactions.