• Journal of the Korean Society of Safety
• /
• v.18 no.1
• /
• pp.94-100
• /
• 2003

Generally, cable-stayed bridges are both statically indeterminate structure with a high degree of redundancy and flexible structure. So it is very important to ensure precision control during both fabrication and construction. In precision control of cable-stayed bridges, precision control under multi-objective programming method is needed, because precision control problem of cable-stayed bridges is a multi-objective programming problem in which many objective functions are regard as variables. In previous studies, it was regarded as a single-objective problem, so it had many problems in respect of usefulness and rationalness. In this study, precision control under multi-objective programming method is proposed considering economy, efficiency, and safety at best in precision control of cable-stayed bridges. Precision control problem of cable-stayed bridges is formulated with satisfying trade-off method which is a kind of multi-objective programming method, then it is optimized with min-max method. A computer program is presented including above process.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.40 no.11
• /
• pp.19-28
• /
• 2003

The limitation on the dynamic range improvement of the complementary correlation optical time domain reflectometer(CCOTDR) is presented. In CCOTDR, the improvement of dynamic range is function of both the averaging number of measurement cycles and the length of codes. The trade off between the averaging number and the code length restricts the improvement of the dynamic range and a very long code is not effective to improve the dynamic range. In this paper, the improvement limitation on dynamic range caused by the trade off between the averaging number and the code length is presented. For derivation of the trade off, the number of one measurement cycles employing a conventional single pulse method and employing a complementary code method are presented and compared. And the effective maximum code length is presented in addition.

• ETRI Journal
• /
• v.31 no.5
• /
• pp.481-488
• /
• 2009

This paper proposes a new multiuser scheduling algorithm that can simultaneously support a variety of different quality-of-service (QoS) user groups while satisfying fairness among users in the same QoS group in MIMO broadcast channels. Toward this goal, the proposed algorithm consists of two parts: a QoS-aware fair (QF) scheduling within a QoS group and an antenna trade-off scheme between different QoS groups. The proposed QF scheduling algorithm finds a user set from a certain QoS group which can satisfy the fairness among users in terms of throughput or delay. The antenna trade-off scheme can minimize the QoS violations of a higher priority user group by trading off the number of transmit antennas allocated to different QoS groups. Numerical results demonstrate that the proposed QF scheduling method satisfies different types of fairness among users and can adjust the degree of fairness among them. The antenna trade-off scheme combined with QF scheduling can improve the probability of QoS-guaranteed transmission when supporting different QoS groups.

• Journal of information and communication convergence engineering
• /
• v.5 no.2
• /
• pp.131-135
• /
• 2007

In this paper, The proposed algorithm consists of three steps. In the first step, TD(Transition Density) calculation has to be performed. a CLB-based CPLD low-power technology mapping algorithm considered a Trade-off is proposed. To perform low-power technology mapping for CPLDs, a given Boolean network has to be represented in a DAG. Total power consumption is obtained by calculating the switching activity of each node in a DAG. In the second step, the feasible clusters are generated by considering the following conditions: the number of inputs and outputs, the number of OR terms for CLB within a CPLD. The common node cluster merging method, the node separation method, and the node duplication method are used to produce the feasible clusters. In the final step, low-power technology mapping based on the CLBs packs the feasible clusters. The proposed algorithm is examined using SIS benchmarks. When the number of OR terms is five, the experiment results show that power consumption is reduced by 30.73% compared with TEMPLA, and by 17.11 % compared with PLA mapping.

• International Journal of Aeronautical and Space Sciences
• /
• v.2 no.2
• /
• pp.73-81
• /
• 2001

This paper describes the procedure to develop a robust estimator design method for a target tracker that accounts for both structured real parameter uncertainties and unknown inputs. Two robust design approaches are combined: the Mini-p-Norm. design method to consider real parameter uncertainties and the $H_{\infty}$ design technique for unknown disturbances and unknown inputs. Constant estimator gains are computed that guarantee the robust performance of the estimator in the presence of parameter variations in the target model and unknown inputs to the target. The new estimator has two design parameters. One design parameter allows the trade off between small estimator error variance and low sensitivity to unknown parameter variations. Another design parameter allows the trade off between the robustness to real parameter variations and the robustness to unknown inputs. This robust estimator design method was applied to the longitudinal motion tracking problem of a T-38 aircraft.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.3
• /
• pp.784-793
• /
• 2012

This paper deals with subcarrier allocation strategies for soft hand-over in OFDMA-based cellular systems. Two possible subcarrier allocation methods are considered for soft hand-over. One method is to use an identical subcarrier set between the two cells participating in the hand-over. The other is to use different subcarrier sets between the two cells. As expected, the different subcarrier strategy is better in terms of diversity order and BER than the identical subcarrier strategy. It will be shown that the BER performance difference between the two strategies is more noticeable with contiguous subcarrier allocation. But the different subcarrier strategy consumes twice more frequency resources than the other, and there is a trade-off between the two strategies in terms of BER and frequency resources. By considering the trade-off, we also propose a subcarrier allocation strategy for soft hand-over.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.1C
• /
• pp.28-36
• /
• 2009

Time-memory trade-off (TMTO) cryptanalysis proposed by Hellman can be applied for the various crypto-systems such as block ciphers, stream ciphers, and hash functions. In this paper, we propose a novel method to reduce memory size for storing TMTO tables. The starting points in a TMTO table can be substituted by the indices of n-bit samples from a sequence in a family of pseudo-random sequences with good cross-correlation, which results in the reduction of memory size for the starting points. By using this method, it is possible to reduce the memory size by the factor of 1/10 at the cost of the slightly increasing of operation time in the online phase. Because the memory is considered as more expensive resource than the time, the TMTO cryptanalysis will be more feasible for many real crypto systems.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.3
• /
• pp.95-100
• /
• 2003

Electronic equipment used in satellites are demanding extremely high reliability, so they should be designed to have immunity for some critical faults by using redundancy component. Generally, Communication satellites are assigned to meet the 15 years mission lifetime, of the analysis about faults must be performed to electronic equipments of satellite. This paper is a summary of the fault tolerance design research of command processor, the improvement of reliability and trade-off study of fault tolerance design result. The reliability prediction value of the satellite component used in this research was taken from Koreasat 3 and Kompsat 1. It is important to perform many trade-off studies for fault tolerance design, especially to choose the most proper fault tolerance method for the specified fault scenario.

• Journal of Mechanical Science and Technology
• /
• v.18 no.8
• /
• pp.1327-1337
• /
• 2004

An efficient multi-objective optimization method is presented making use of neural network and a systematic satisficing trade-off method (STOM), in order to simultaneously improve both maneuverability and durability of tire. Objective functions are defined as follows: the sidewall-carcass tension distribution for the former performance while the belt-edge strain energy density for the latter. A back-propagation neural network model approximates the objective functions to reduce the total CPU time required for the sensitivity analysis using finite difference scheme. The satisficing trade-off process between the objective functions showing the remarkably conflicting trends each other is systematically carried out according to our aspiration-level adjustment procedure. The optimization procedure presented is illustrated through the optimum design simulation of a representative automobile tire. The assessment of its numerical merit as well as the optimization results is also presented.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.23 no.6
• /
• pp.582-590
• /
• 2020

This paper presents the results of new error analysis on the veering of marine target with the concept of frequency of occurrence, and shows how to apply the midcourse guidance errors of anti-ship missile. The veering error would be a dominant factor in the midcourse guidance errors with flight time increase. This study suggests the reasonable application method of the veering error based on the characteristics of abnormal error, and describes the tailoring method including trade-off between the midcourse guidance range of veering target and the value of frequency of occurrence on veering error.