• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.12 no.6
• /
• pp.3-15
• /
• 2002

In this paper, we propose an efficient and secure sealed-bid auction protocol with two servers, a seller S and a third party A . The proposed scheme uses the idea of the conditional oblivious transfer protocol proposed by Crescenzo-Ostrovskey-Rajagopalan. A server A is not a trusted third party, but is assumed not to collude with a server S. In the proposed auction protocol, barring collusion between A and S, neither party gains any information about the bids, and moreover, the outcome of the auction will be correct. And the computational complexity of our auction protocol is considerably efficient and the communication overhead is similar to that of Naor-Pinkas-Sumner's scheme.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.4
• /
• pp.679-685
• /
• 2010

As the electrical power industry is restructured, the electrical power exchange is becoming extended. One of the key information used to determine how much power can be transferred through the network is known as available transfer capability (ATC). To calculate ATC, traditional deterministic approach is based on the severest case, but the approach has the complexity of procedure. Therefore, novel approach for ATC calculation is proposed using cost-optimization method, well-being method and risk-benefit method in this paper. This paper proposes the optimal transfer capability of HVDC system between mainland and a separated island in Korea through these three methods. These methods will consider production cost, wheeling charge through HVDC system and outage cost with one depth (N-1 contingency).

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.195_196
• /
• 2009

As the electrical power industry is restructured, the electrical power exchange is becoming extended. One of the key information used to determine how much power can be transferred through the network is known as available transfer capability (ATC). To calculate ATC, traditional deterministic approach is based on the severest case, but the approach has the complexity of procedure. Therefore, novel approach for ATC calculation is proposed using cost-optimization method in this paper, and is compared with well-being method and risk-benefit method. This paper proposes the optimal transfer capability of HVDC system between mainland and a separated island in Korea through these three methods. These methods will consider production cost, wheeling charge through HVDC system and outage cost with one depth (N-1 contingency).

• ETRI Journal
• /
• v.43 no.2
• /
• pp.221-231
• /
• 2021

To resolve energy depletion issues in massive Internet of Things sensor networks, we developed a set of distributed energy beamforming methods with one-bit feedback and clustering for multi-node wireless energy transfer, where multiple singleantenna distributed energy transmitters (Txs) transfer their energy to multiple nodes wirelessly. Unlike previous works focusing on distributed information beamforming using a single energy receiver (Rx) node, we developed a distributed energy beamforming method for multiple Rx nodes. Additionally, we propose two clustering methods in which each Tx node chooses a suitable Rx node. Furthermore, we propose a fast distributed beamforming method based on Tx sub-clustering. Through computer simulations, we demonstrate that the proposed distributed beamforming method makes it possible to transfer wireless energy to massive numbers of sensors effectively and rapidly with small implementation complexity. We also analyze the energy harvesting outage probability of the proposed beamforming method, which provides insights into the design of wireless energy transfer networks with distributed beamforming.

• Journal of Korea Multimedia Society
• /
• v.10 no.12
• /
• pp.1612-1621
• /
• 2007

In this paper, we introduced our designed TDMA (Time Division Multiple Access) based MAC (Medium Access Control) protocol for Home Networks called HomeTDMA. We have implemented and tested it in a test bed using crossbow motes and TinyOS. We also have compared HomeTDMA and CSMA (Carrier Sense Multiple Access) in terms of space and time complexity, channel access time, delivery success ratio, and throughput. Based on our results, HomeTDMA has an advantage over CSMA on channel access time, throughput and delivery success ratioIn the case of complexity, HomeTDMA is more complex compared to CSMA. Thus, CSMA is more appropriate in wireless sensor networks (WSNs) where memory, energy, and throughput are important parameters to be considered. However, HomeTDMA has a natural advantage of collision free medium access and is very promising for home networks where a reliable transmission or data transfer and congestion control is highly preferred.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.7
• /
• pp.928-938
• /
• 1997

The end winding is an important part in induction motor for thermal analysis. But there is little information on the heat transfer coefficient of that surfaces because of geometrical complexity. So our experimental object is to know the heat transfer coefficient of end winding and find the optimum design parameter of rotor fan. Carbon coated papers were used for a uniform heat generating surfaces which were easy to fabricate. The experiments of some parameters were performed as varying rotation speed of rotor fan. We obtained the local and average Nusselt number of the end winding surfaces by correcting radiation and conduction losses errors. The results showed that the average Nusselt number increased with rotor fan blade number and width but decreased with end winding length. However, the increasing limits existed in the case of rotor fan width and blade number. So optimum design value were obtained for rotor fan width and blade numbers.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.4
• /
• pp.118-127
• /
• 1998

In this paper, we propose a voice personality transformation method which makes one person's voice sound like another person's voice. In order to transform the voice personality, vocal tract transfer function is used as a transformation parameter. Comparing with previous methods, the proposed method can obtain high-quality transformed speech with low computational complexity. Conversion between the vocal tract transfer functions is implemented by a linear mapping based on soft clustering. In this process, mean LPC cepstrum coefficients and mean removed LPC cepstrum modeled by the low dimensional vector are used as transformation parameters. To evaluate the performance of the proposed method, mapping rules are generated from 61 Korean words uttered by two male and one female speakers. These rules are then applied to 9 sentences uttered by the same persons, and objective evaluation and subjective listening tests for the transformed speech are performed.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.4
• /
• pp.193-198
• /
• 2005

As the electrical power industry is restructured, the electrical power exchange is extended. One of the key information used to determine how much power can be transferred through the network is known as available transfer capability (ATC). To calculate ATC, traditional deterministic approach is based on the severest case, but the approach has the complexity of procedure. Therefore, novel approach for ATC calculation is proposed using cost optimization in this paper Cheju Island interconnected HVDC system with mainland in KEPCO (Korean Electric Power Corporation) systems, and the demand of Cheju Island increases about 10 ($\%$) every year. To supply for increasing demand, the supply of HVDC system must be increased. This paper proposed the optimal transfer capability of HVDC system between Haenam in mainland and Cheju in Chju Island through cost optimization. The cost optimization is considered production cost in Cheju Island, wheeling charge through Haenam-Cheju HVDC system and outage cost with one depth (N-1 contingency)

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.12
• /
• pp.2321-2328
• /
• 2006

Today, SIP standard (The signalling protocol for the Internet phone service) raises to be the standard technique because the expandability is high and complexity is low. It is widely investigated and actively advocated to use Si81a1 ring protocol for SIP in VoIP service. SIP service can be applied even outside the Internet phone service; instance messaging and various multimedia technology are just an example. This paper proposed an embodiment proxy server for rambling support to use JAIN SIP API. It provides standard interface for testing the Proxy server for SIP and embodiment of user agent that transfer instant massaging and voice communication.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.3
• /
• pp.523-529
• /
• 2017

In this paper, we propose an efficient sphere decoding scheme that reduces computational complexity by combining receive and transmit ordering techniques in generalized spatial modulation systems, where the indexes of activated transmit antennas as well as the transmit symbols are exploited to transfer information to the receiver. In this scheme, the receive signals are optimally ordered so that the calculation for a candidate solution outside the sphere is terminated early to lower the computational complexity. In addition, the transmit ordering technique is applied to first search for candidate symbols and activated antennas having higher probabilities to further reduce the computational complexity. Simulation results show that the proposed doubly ordered sphere decoding scheme provides the same bit error rate performance with the conventional sphere decoding method and the sphere decoder employing only the receive ordering technique while it requires lower computational complexity.