• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.59-65
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• 2008

In this paper, a new adaptive resource allocation scheme is proposed in orthogonal frequency-division multiple access(OFDMA) systems with rate proportionality constraints. The problem of maximizing the overall system capacity with constraints on bit error rate, total transmission power and rate-proportionality for user requiring different classes of service is formulated. Since the optimal solution to the constrained fairness problem is extremely complex to obtain, a low-complexity suboptimal algorithm that separates subchannel allocation and power allocation is proposed. Firstly, the number of subchannels to be assigned to each user is determined based on the users' average signal-to-noise ratio and rate-proportion. Subchannels are subsequently distributed according to the modified max-min criterion. Lastly, based on the subchannel allocation, the optimal power allocation by solving the Language dual problem is proposed. Additionally, in order to reduce the computational complexity, iterative rate proportionality tracking algorithm is proposed for maximizing the capacity together with maintaining the rate proportionality constraint.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.9
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• pp.1654-1665
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• 2008

This paper presents bit splitting methods to apply multilevel modulation to iterative codes such as turbo code, low density parity check code and turbo product code. Log-likelihood ratio method splits multilevel symbols to soft decision symbols using the received in-phase and quadrature component based on Gaussian approximation. However it is too complicate to calculate and to implement hardware due to exponential and logarithm calculation. Therefore this paper presents Euclidean, MAX, sector and center focusing method to reduce the high complexity of LLR method. Also, this paper proposes optimal soft symbol split method for three kind of iterative codes. Futhermore, 16-APSK modulator method with double ring structure for applying DVB-S2 system and 16-QAM modulator method with lattice structure for T-DMB system are also analyzed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.143-152
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• 2013

Given weighted graph G=(V,E), n=|V|, m=|E|, the minimum cut problem is classified with source s and sink t or without s and t. Given undirected weighted graph without s and t, Stoer-Wagner algorithm is most popular. This algorithm fixes arbitrary vertex, and arranges maximum adjacency (MA)-ordering. In the last, the sum of weights of the incident edges for last ordered vertex is computed by cut value, and the last 2 vertices are merged. Therefore, this algorithm runs $\frac{n(n-1)}{2}$ times. Given graph with s and t, Ford-Fulkerson algorithm determines the bottleneck edges in the arbitrary augmenting path from s to t. If the augmenting path is no more exist, we determine the minimum cut value by combine the all of the bottleneck edges. This paper suggests minimum cut algorithm for undirected weighted graph with s and t. This algorithm suggests MA-merging and computes cut value simultaneously. This algorithm runs n-1 times and successfully divides V into disjoint S and V sets on the basis of minimum cut, but the Stoer-Wagner is fails sometimes. The proposed algorithm runs more than Ford-Fulkerson algorithm, but finds the minimum cut value within n-1 processing times.

• Journal of Korea Spatial Information System Society
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• v.9 no.1
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• pp.79-90
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• 2007

In this paper we proposed and implemented an incident detection model which combines fuzzy algorithm and traffic pattern in order to enhance the efficiency of incident detection for the highways with lamps. Most of the existing algorithms dealt with highways without lamps and can not be used for detecting incidents in the highways with lamps. The data used for model building are traffic volume, occupancy, and speed data. They have been collected by a loop sensor at 5 minutes interval at a point in the Internal Circular Highway of Seoul for the period of 3 months. In this model, the three parameters collected by sensor were fuzzified and combined with the daily traffic pattern of the link. The test of efficiency of the propsed model was performed by comparing the result of proposed model with traditional APID algorithm and fuzzy algorithm without the pattern data respectively. The result showed significant amount of improvement in reducing the false incident detection rate by 18%.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.55-60
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• 2011

In this paper, we propose a new method for extracting muscles from lumbar images. The proposed method sets areas without distortions with field expert's assistance as areas of measuring interest and removing noises from initial ultrasonic videos. Then, the method emphasizes the brightness contrast with Ends-in search stretching algorithm and separate thoracic vertebra from subcutaneous fat area using morphological characteristics. 4-directions contour tracing algorithm is applied to extract the bottom of subcutaneous fat area. Extracting thoracic vertebra area requires noise removal and morphological characteristics as well among candidate areas obtained by controlling min-max brightness. The thickness of muscles is then defined as the length between subcutaneous fat area and extracted thoracic vertebra. The experiment which consists of 368 image analysis verifies that the proposed method is more effective in measuring the thickness of muscles than before.

• Journal of the Korean Institute of Navigation
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• v.15 no.2
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• pp.39-47
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• 1991

As per the rapid development of world economics the marine traffic volume was increased accordingly and caused frequent disasters in human lives and natural environment in the consequence of accidents. As the result of the above they started to establish Vessel Traffic System(VTS) and separation scheme in waterway from 1960' to prevent the marin traffic accident but the problem of safety at sea appears now as neither fully defined nor sufficiently analysed. At the present, the dominant factor in establishing the strategy of marine traffic has been safety of navigation concerning only with the ship, but the risk of society derives almost wholly from the nature of cargo. To measure the degree of danger for each ship there is suggested concept of safety factor numbers denoting the level of latent danger in connection with ship and her cargo. In this paper, where the strategy of VTS is put on controlling density of safety factor for control area. it suggested algorithms how to assign the vessels and also to get optimal sequence of vessels located to a sector in the sense of minimizing the passage delay. For the formulation of problem, min max and 0-1 programming methods are applied and developed heuristic algorithm is presented with numerical example to improve the efficiency of calculation.

• Journal of Power Electronics
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• v.15 no.3
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• pp.660-669
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• 2015

This paper presents a control scheme with a focus on the combination of phase disposition pulse width modulation (PDPWM) and DC capacitor voltage control for a chopper-cell based modular multilevel converter (MMC) for the purpose of eliminating the time-consuming voltage sorting algorithm and complex voltage balancing regulators. In this paper, the convergence of the DC capacitor voltages within one arm is realized by charging the minimum voltage module and discharging the maximum voltage module during each switching cycle with the assistances of MAX/MIN capacitor voltage detection and PDPWM signals exchanging. The process of voltage balancing control introduces no extra switching commutation, which is helpful in reducing power loss and improving system efficiency. Additionally, the proposed control scheme also possess the merit of a simple executing procedure in application. Simulation and experimental results indicates that the MMC circuit together with the proposed method functions very well in balancing the DC capacitor voltage and improving system efficiency even under transient states.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.6
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• pp.2546-2566
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• 2016

This paper investigates an efficient transmission scheme for the remote wireless sensors to receive information which is rarely discussed in the integrated remote wireless sensor and multibeam satellite networks (IWSMSNs). The networks can be employed to exchange sensing information for emergency scenario, ocean scenario, and so on, which are isolated from available terrestrial networks. As the efficient transmission link is important to the IWSMSNs, we propose a hybrid full frequency (HFF) precoding by taking advantage of frequency reuse and multiple-input multiple-output (MIMO) precoding. Considering energy efficiency and sinks fairness are crucial to transmission link, thus the HFF precoding problems are formulated as transmit power minimization (TPM) and max-min fair (MMF) received signal to interference plus noise ratio (SINR) problems, which can be transformed to indefinite quadratic optimization programs. Then this paper presents a semi-definite programming (SDP) algorithm to solve the problems for the IWSMSNs. The promising potential of HFF for the real IWSMSNs is demonstrated through simulations.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.7
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• pp.38-50
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• 1997

This paper concerns a VHDL design and simulation of an accurate and cost-effective fuzzy logic controller (FLC). The accurcy of the proposed FLC is obtained by using the center of gravity (COG) defuzzifier that considers both membership values and spans of membership functions in calculating a crisp value. The cost-effectiveness of the proposed FLC is obtained by restructuring the conventional FLC in the following ways: Firstly, the MAX-MIN inference is inference is replaced by a read-modify-write operation that can be implemented economically in the structure of register files. Secondly, the division in the COG defuzzifier is avoided by finding the moment equilibrium point. The proposed COG defuzzifier has two disadvantages that it requires additional multipliers and it takes a lot of computation time to find the moment equilibrium point. The first disadvantage is overcome by replacing the mulitpliers with stochastic AND operations and the second disadvantage is alleviated by using a coarse-to-fine searching algorithm. The proposed FLC is described in VHDL structurally and behaviorally and whether it is working well or not is checked on SYNOPSYS VHDL simulator by using the truck backer-upper control problem.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.10
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• pp.410-417
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• 2006

Generally, the training set of maximum $m{\times}L(m+f)$ patterns in the pattern recognition method is required for the real-time bus reconfiguration strategy when a main transformer fault occurs in the distribution substation. Accordingly, to make the application of pattern recognition method possible, the size of the training set must be reduced as efficient level. This Paper proposes a methodology which obtains the minimized training set by applying the pattern clustering method to load patterns of the main transformers and feeders during selected period and to obtain bus reconfiguration strategy based on it. The MaxMin distance clustering algorithm is adopted as the pattern clustering method. The proposed method reduces greatly the number of load patterns to be trained and obtain the satisfactory pattern matching success rate because that it generates the typical pattern clusters by appling the pattern clustering method to load patterns of the main transformers and feeders during selected period. The proposed strategy is designed and implemented in Visual C++ MFC. Finally, availability and accuracy of the proposed methodology and the design is verified from diversity simulation reviews for typical distribution substation.