• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.10
• /
• pp.1014-1022
• /
• 2009

A biped robot in locomotion can be regarded to be kinetically redundant in that the link-chain from its foot on the ground to its swing foot has more degrees of freedom that needed to realize stable bipedal locomotion. This paper proposes a new method to generate a trajectory for bipedal locomotion based on this redundancy, which directly generates a locomotion trajectory at the joint level unlike some other methods such as LIPM (linear inverted-pendulum mode) and GCIPM (gravity-compensated inverted-pendulum mode), each of which generates a trajectory of the center of gravity or the hip link under the assumption of the dominance of the hip-link inertia before generating the trajectory of the whole links at the joint level. For the stability of the trajectory generated in the proposed method, a stability condition based on the ZMP (zero-moment point) is used as a constraint as well as other kinetic constraints for bipedal motions. A 6-DOF biped robot is used to show how a stable locomotion trajectory can be generated in the sagittal plane by the proposed method and to demonstrate the feasibility of the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.5 no.5
• /
• pp.1013-1027
• /
• 2011

In this paper we propose ATCS, a practical TCP protocol coding scheme based on network coding for satellite IP networks. The proposal is specially designed to enhance TCP performance over satellite networks. In our scheme, the source introduces a degree of redundancy and transmits a random linear combination of TCP packets. Since the redundant packets are utilized to mask packet loss over satellite links, the degree of redundancy is determined by the link error rates. Through a simple and effective method, ATCS estimates link error rates in real time and then dynamically adjusts the redundant factor. Consequently, ATCS is adaptable to a wide range of link error rates by coding TCP segments with a flexible redundancy factor. Furthermore, the scheme is compatible with traditional TCP variants. Simulation results indicate that the proposal improves TCP performance considerably.

• Industrial Engineering and Management Systems
• /
• v.15 no.3
• /
• pp.259-267
• /
• 2016

In Wireless Sensor Network, various routing protocols were employed by our Research and Development community to improve the energy efficiency of a network as well as to control the traffic by considering the terms, i.e. Packet delivery rate, the average end-to-end delay, network routing load, average throughput, and total energy consumption. While maintaining network connectivity for a long-term duration, it's necessary that routing protocol must perform in an efficient way. As we discussed Optimized Link State Routing protocol between all of them, we find out that this protocol performs well in the large and dense networks, but with the decrease in network size then scalability of the network decreases. Whenever a link breakage is encountered, OLSR is not able to periodically update its routing table which may create a redundancy problem. To resolve this issue in the OLSR problem of redundancy and predict link breakage, an enhanced protocol, i.e. S-OLSR (More Scalable OLSR) protocol has been proposed. At the end, a comparison among different existing protocols, i.e. DSR, AODV, OLSR with the proposed protocol, i.e. S-OLSR is drawn by using the NS-2 simulator.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.05a
• /
• pp.811-814
• /
• 2009

The HF band maritime communication is have developing to digital methode that techniques should be readied the automatic link establishment of 1:N by coast station to many ship station. Because can use way by polling simply that communication environment calls particular station wicked fellow HF communication states which is much redundancy times for coast station to set link. In amateur radio particular station selective calling do to be using ALE(Automatic Link Establishment) controller by 1:1 automatic link setting way, but expect 1:N link setting by these way in maritime communication very difficult. That is difficult to avoid collision by traffic overload to induce calling of ship stations. Because HF communication considers channel special quality traffic state radio link should be established, and should be applied automatically secures stability of channel as accommodative at traffic overload. In this paper is studied the new radio protocol by 3 step sequency driving of free access, group free access and polling access using multi-tone in single channel.

• Proceedings of the IEEK Conference
• /
• 2002.06a
• /
• pp.247-250
• /
• 2002

It is predicted that the existing backbone network has encountered its limit due to massive growth in data traffic. Perhaps new WDM methods utilizing optical fibers are desirable. Also to assure reliance of the network detour routes fur collision recovery must be considered. But due to the redundancy occurred by allocating bandwidths to the detour route, the efficiency of the link my decline. In this paper, we designed a detour route to minimize the redundancy.

• ETRI Journal
• /
• v.33 no.2
• /
• pp.210-218
• /
• 2011

Battiti's mutual information feature selector (MIFS) and its variant algorithms are used for many classification applications. Since they ignore feature synergy, MIFS and its variants may cause a big bias when features are combined to cooperate together. Besides, MIFS and its variants estimate feature redundancy regardless of the corresponding classification task. In this paper, we propose an automated greedy feature selection algorithm called conditional mutual information-based feature selection (CMIFS). Based on the link between interaction information and conditional mutual information, CMIFS takes account of both redundancy and synergy interactions of features and identifies discriminative features. In addition, CMIFS combines feature redundancy evaluation with classification tasks. It can decrease the probability of mistaking important features as redundant features in searching process. The experimental results show that CMIFS can achieve higher best-classification-accuracy than MIFS and its variants, with the same or less (nearly 50%) number of features.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38A no.8
• /
• pp.662-668
• /
• 2013

Mobile communication systems have been adopting link adaptive transmission schemes such as adaptive modulation and coding (AMC) and hybrid-ARQ (HARQ). Incremental redundancy (IR) HARQ scheme is known to be highly efficient in terms of throughput and power consumption and can be a good solution for mobile communication systems. In this paper, we propose an IR-HARQ scheme based on dual-diagonal parity-type block LDPC codes in which we define a transmission priority of coded bits and propose the sub-packet construction rule. We present the throughput performance of IR-HARQ with various modulation and coding and multi-antenna modes. Consequently, the proposed scheme provides the improvement of system throughput by elaborate link adaptation with CQI information.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.2 no.4
• /
• pp.194-208
• /
• 2008

In this paper, a multiple-input-multiple-output (MIMO) hybrid-automatic repeat request (HARQ) algorithm with antenna scheduling is proposed. It retransmits the packet using scheduled transmit antennas according to the state of the communication link, instead of retransmitting the packet via the same antennas. As a result, a combination of conventional HARQ systems, viz. chase combining (CC) and incremental redundancy (IR) are used to achieve better performance and lower redundancy. The proposed MIMO-OFDM HARQ system with antenna scheduling is shown to be superior to conventional MIMO HARQ systems, due to its spatial diversity gain.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.27 no.7
• /
• pp.59-66
• /
• 2013

This paper proposes a new voltage reference generation method for Four-Switch Inverters(FSI) with compensation of the neutral DC-link voltage variation. Since FSIs have the split DC-link causing the inherent problem of voltage fluctuations in the upper and lower capacitors, it is required to take account the voltage difference between the top and bottom capacitors. In this paper, to reduce the effect by the voltage variation, reference voltages are modified by adding compensation voltages proportional to the voltage difference between upper and lower capacitors. Simulation results showing control performance of induction and permanent magnet motors demonstrate the validity of the proposed method.

• Proceedings of the IEEK Conference
• /
• 2003.07d
• /
• pp.1319-1322
• /
• 2003

We present a web document summarizer, simpler more condense than the existing ones, of a search engine. This summarizer generates summaries with a statistic-based summarization method using Clustering or MMR technique to reduce redundancy in the results, and that generates summaries using Perfect Link Graph. We compare the results with the summaries generated by human subjects. For the comparison, we use FScore. Our experimental results verify the accuracy of the summarization methods.