• Journal of Ocean Engineering and Technology
• /
• v.24 no.6
• /
• pp.16-22
• /
• 2010

In this paper, the diffraction problems for fixed offshore structures are solved using a hybrid scheme. In this hybrid scheme, potential-based solutions and the Navier-Stokes-based finite volume method (FVM) with a volume-of-fluid (VOF) method are combined. We introduce a buffer zone for efficient wave-making and damping. In this buffer zone, the near field solution from FVM-VOF is gradually changed to Stokes' 2nd order wave solutions. Three different models, including the truncated cylinder, sphere, and wigleyIII model, are numerically investigated in regular waves with a wave steepness of 1/30. The efficiency and accuracy of the hybrid scheme are numerically validated from results using different domain sizes and buffer zones. The wave exciting forces from the FVM-VOF simulations are compared with experiments and potential-based solutions from the higher-order boundary element method (HOBEM). This comparison shows good agreement between the hybrid scheme and potential-based solutions.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.4C
• /
• pp.426-433
• /
• 2006

In this paper, we propose an incremental redundancy(IR)-hybrid ARQ(HARQ) scheme which uses double binary turbo codes for error correction. We also propose a methodology for basic analysis of the throughput which is a performance index of HARQ. The proposed double binary turbo IR-HARQ scheme provides higher throughput than binary IR-HARQ, which uses binary turbo codes for error correction, at all $E_s/N_0$. An extra coding gain is also attained by using the proposed HARQ scheme over the coding gain achieved by turbo codes only.

• Communications for Statistical Applications and Methods
• /
• v.27 no.4
• /
• pp.413-430
• /
• 2020

The multiply Type-II hybrid censoring scheme is disadvantaged by an experiment time that is too long. To overcome this limitation, we propose a generalized multiply Type-II hybrid censoring scheme. Some estimators of the scale parameter of the exponential distribution are derived under a generalized multiply Type-II hybrid censoring scheme. First, the maximum likelihood estimator of the scale parameter of the exponential distribution is obtained under the proposed censoring scheme. Second, we obtain the Bayes estimators under different loss functions with a noninformative prior and an informative prior. We approximate the Bayes estimators by Lindleys approximation and the Tierney-Kadane method since the posterior distributions obtained by the two priors are complicated. In addition, the Bayes estimators are obtained by using the Markov Chain Monte Carlo samples. Finally, all proposed estimators are compared in the sense of the mean squared error through the Monte Carlo simulation and applied to real data.

• Journal of the Korean Data and Information Science Society
• /
• v.25 no.2
• /
• pp.431-438
• /
• 2014

Type I hybrid censoring scheme is the combination of the Type I and Type II censoring scheme introduced by Epstein (1954). Epstein considered a hybrid censoring sampling scheme in which the life testing experiment is terminated at a random time $T^*$ which is the time that happens rst among the following two; time of the kth unit is observed or time of the experiment length set in advance. The likelihood function of this scheme from the Rayleigh distribution cannot be solved in a explicit solution and thus we approximate the function by the Taylor series expansion. In this process, we propose four dierent methods of expansion skill.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.7
• /
• pp.12-21
• /
• 2002

In this paper, we propose a new hybrid ARQ scheme to consider real-time and non real-time services in a wireless ATM network. Real-time and non-real-time services require different error control schemes according to each service characteristics. Therefore, in the next generation mobile communication environments where these service scenarios should be deployed, hybrid ARQ scheme using RCPC code with variable coding rate becomes one of the most suitable solutions. Because the variable coding rate is applied according to traits of transmitted frame and channel status, hybrid ARQ scheme using RCPC code can expect UEP effect. The UEP scheme does not apply equal error protection level to all information, but does high error protection level to more important information. In Our scheme, UEP of high error protection level is applied to real-time service, and UEP of low error protection and retransmission techniques are applied to non real-time service. We show that the proposed hybrid ARQ scheme improves channel utilization efficiency and yields high error correction behaviors.

• 제어로봇시스템학회:학술대회논문집
• /
• 1992.10a
• /
• pp.638-641
• /
• 1992

In this paper, a hybrid position/force control scheme is proposed. The control scheme modifies the position command for force control against constraint surface of environment and is very simply designed and implemented. The merits of the control scheme are that it can cope with change of constraint conditions and small position inaccuracy of the environment. A constraint surface position observer is also proposed to reduce disturbances on controlled force.

• The Pure and Applied Mathematics
• /
• v.21 no.3
• /
• pp.195-206
• /
• 2014

In this paper, we consider, under a hybrid iterative scheme with errors, a weak convergence theorem to a common element of the set of a finite family of asymptotically k-strictly pseudo-contractive mappings and a solution set of an equilibrium problem for a given bifunction, which is the approximation version of the corresponding results of Kumam et al.

• Journal of Internet Computing and Services
• /
• v.10 no.6
• /
• pp.173-189
• /
• 2009

Recently, video data has attracted many interest. That is the reason why efficient indexing schemes are required to support the content-based retrieval of video data. But most indexing schemes are not suitable for indexing a high-dimensional data except Hybrid Spill-Tree. In this paper, we propose an efficient high-dimensional indexing scheme to support the content-based retrieval of video data. For this, we extend Hybrid Spill-Tree by using a newly designed clustering technique and by adopting a signature method. Finally, we show that proposed signature-based high dimensional indexing scheme achieves better retrieval performance than existing M-Tree and Hybrid Spill-Tree.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.743-746
• /
• 1996

A hybrid control scheme to regulate the force and position by dual arms is proposed, where two arms are treated as one arm in a kinematic viewpoint. Our approach is different from other hybrid control approaches which consider robot dynamics, in the sense that we employ a purely kinematic based approach for hybrid control, with regard to the nature of position-controlled industrial robots. The proposed scheme is applied to sawing task. In the sawing task, the trajectory of the saw grasped by dual arms is planned in an offline fashion. When the trajectory of the saw is planned to follow a line in a horizontal plane, 3 position parameters are to be controlled(i.e, two translational positions and one rotational position). And a certain level of contact force has to be controlled along the vertical direction(i.e., minus z-direction) not to loose the contact with the object to be sawn. Typical feature of sawing task is that the contact position where the force control is to be performed is continuously changing. Therefore, the kinematic mapping between the force controlled position and the joint actuators has to be updated continuously. The effectiveness of the proposed control scheme is experimentally demonstrated. The proposed hybrid control scheme can be applied to arbitrary dual arm systems, regardless of their kinematic structure and the number of actuated joints.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.17 no.3
• /
• pp.336-341
• /
• 2014

When using a higher-order modulation scheme, there are variations in bit-reliability depending on the bit position in a modulation symbol. Variations of bit-reliability in the codeword block lower the decoding performance. Also, the decoding performance increases as the sum of the bit-reliabilities in the codeword block increases. This paper presents a novel hybrid automatic repeat request scheme that increases the sum of the reliabilities of the transmitted bits by lowering the modulation order, and decreases the variations of bit-reliability in the codeword block by preferentially retransmitting bits with low reliability. The proposed scheme outperforms the constellation rearrangement scheme. Furthermore, the proposed scheme also provides a good solution in cases where the size of the retransmission block is smaller than the size of the initial transmission block.