• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.746-760
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• 1998

In this paper, an adaptive RSSD(reduced-state sequence detection) receiver is proposed for the purpose of reducing the complexity and decision delay of the adaptive MLSD(maximum-likelihood sequence detection) receiver in the mobile satellite channel. The RSSD receiver reconstructs the trellis with a reduced number of states. The performance degradation due to the reduced states is compensated by modifying the branch metric calculation which uses the symbols in each path memory to estimate the residual ISI(intersymbol interference) terms. The structure of the proposed adaptive RSSD is a modified RSSD utilizing a per-survivor processing as well as the symbol-aided method and a channel estimation using the tentative data sequences. The complexity and performance of the proposed adaptive RSSD are controlled by the number of system states and ISI cancelers and the inserting period of the known symbols. In spite of a suboptimal alternative receiver compared to the adaptive MLSD receiver, the proposed adaptive RSSD receiver is able to reduce the complexity significantly and track the time-varying channel fast and reliably.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.430-435
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• 2018

In this paper, an improved decoding scheme for low-complexity parity-check(LCPC) code with small code length is proposed. The LCPC code is less complex than the turbo code or low density parity check(LDPC) code and requires less memory, making it suitable for communication between internet-of-things(IoT) devices. The IoT devices are required to have low complexity due to limited energy and have a low end-to-end delay time. In addition, since the packet length to be transmitted is small and the signal processing capability of the IoT terminal is small, the LCPC coding system should be as simple as possible. The LCPC code can correct all single errors and correct some of the two errors. In this paper, the proposed decoding scheme improves the bit error rate(BER) performance without increasing the complexity by correcting both errors using the soft value of the modulator output stage. As a result of the simulation using the proposed decoding scheme, the code gain of about 1.1 [dB] was obtained at the bit error rate of $10^{-5}$ compared with the existing decoding method.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.3
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• pp.351-355
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• 2010

The service which is required wide bandwidth is growing in these days, so building up High Speed communication system is being required. The Task Force team of IEEE 802.3ah set the EPON as a standard; next generation subscriber access network. For offering a high quality service, 10G EPON that is changed from 1Gbps uplink downlink bandwidth to 10Gbps is come up. Although Kramer had studied 10G EPON there was a QoS limitation, when load is low, End-to-End maximum delay is increased. This paper is suggesting time synch ronization method, resource reservation method, band width allocation method. We confirmed that 10EPON was able to offer quality service by the result of the OPNET.

• The Journal of the Acoustical Society of Korea
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• v.20 no.6
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• pp.87-93
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• 2001

As a new type of a linear decorrelating receiver, the Pseudo-Decorrelator was presented for asynchronous code division multiple access systems by the author. In this paper, the concept of the Pseudo-Decorrelator is extended to derive a receiver for WCDMA uplink systems over an additive white Gaussian noise channel. Starting with the analysis of the multiple access components of the decision statistics, a non-square cross-correlation matrix for each bit is obtained. This cross-correlation matrix is then inverted, and the inverted matrix is applied to the decision statistics obtained from a conventional receiver. In this receiver, the detection process can be started after the first three consecutive bits are received. Simulation results are presented for K-user systems over an additive white Gaussian noise channel under the circumstances in which synchronization errors, including time delay errors and carrier phase errors exist. It is shown that the proposed receiver performs better than a conventional receiver and parallel interference canceller.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1950-1958
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• 2016

Today, technique for precisely positioning vehicles is very important in C-ITS(Cooperative Intelligent Transport System), Self-Driving Car and other information technology relating to transportation. Though the most popular technology for vehicle positioning is the GPS, its accuracy is not reliable because of large delay caused by multipath effect, which is very bad for realtime traffic application. Therefore, in this paper, we proposed the Vision-Based High Accuracy Vehicle Positioning Technology. At the first step of proposed algorithm, the ROI is set up for road area and the vehicles detection. Then, center and four corners points of found vehicles on the road are determined. Lastly, these points are converted into aerial view map using homography matrix. By analyzing performance of algorithm, we find out that this technique has high accuracy with average error of result is less than about 20cm and the maximum value is not exceed 44.72cm. In addition, it is confirmed that the process of this algorithm is fast enough for real-time positioning at the $22-25_{FPS}$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.89-98
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• 2000

This paper presents an active noise cancelling model using wavelet transform and subband filter banks based on adaptive filter. The analysis filter banks decompose input and error signals into QMF filter banks of lowpass and highpass bands. Each filter bank uses wavelet filter with dyadic tree structure. The decomposed input and error signals are iterated by adaptive filter coefficients of each subband using filtered-X LMS algorithm. The synthesis filter banks make output signal of wideband with perfect reconstruction to prepare adaptive filter output signals of each subband. The analysis and synthesis niter hants use conjugate quadrature filters for Pefect reconstruction. Also, The delayed LMS algorithm model for on-line identification of error path transfer characteristics is used gain and acoustic time delay factors. The proposed adaptive active noise cancelling modelis suggested by system retaining the computational and convergence speed advantage using wavelet subband filter banks.

• Journal of Information Management
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• v.18 no.4
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• pp.98-117
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• 1985

At the present time, the role and importance of information retrieval has greatly increased for two main reasons: the coverage of the searchable collections is now extensive and collection size may exceed several million documents; further more, the search results can now be obtained more or less instantaneously using online procedures and computer terminal devices that provide interaction and communication between system and users. The large collection size make it plausible to the users that relevant information will in fact be retrieved as a result of a search operation, and the probability of obtaining the search output without delay creates a substantial user demand for the retrieval services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.821-835
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• 1998

The Digital Audio-Visual Council(DAVIC) that was established to develop useful multimedia communication services has completed the specifications for providing on-demand services such as Movie on Demand(MoD), Teleshopping and accepting Internet service. And then they are proceeding the works to suport converstional communcation services like Plain Old Telecphone Service(POTS), Video telephone, Video teleconferencing. In this paper, we prpose an efficient terminal architecture which can provide conversational multimedia communication services on DAVIC Set-Top Box (STB) environments. To apply the implemented conversational terminal to the multipoint communication environment, we considered the factors of Qurlity of Services(QoS) that determine grade of conversational communication service. We also present the inter-working scheme and that system structure to satisfy QoS by using new MPEG video bridge which gurantees end to end delay requirements as major element of QoS for achieving the real time communication and does not accompany visual quality degradation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.2
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• pp.111-120
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• 2017

This paper proposes an improved standard genetic algorithm (GA) of making a near optimal schedule for integrated process planning and scheduling problem (IPPS) considering tool flexibility and tool related constraints. Process planning involves the selection of operations and the allocation of resources. Scheduling, meanwhile, determines the sequence order in which operations are executed on each machine. Due to the high degree of complexity, traditionally, a sequential approach has been preferred, which determines process planning firstly and then performs scheduling independently based on the results. The two sub-problems, however, are complicatedly interrelated to each other, so the IPPS tend to solve the two problems simultaneously. Although many studies for IPPS have been conducted in the past, tool flexibility and capacity constraints are rarely considered. Various meta-heuristics, especially GA, have been applied for IPPS, but the performance is yet satisfactory. To improve solution quality against computation time in GA, we adopted three methods. First, we used a random circular queue during generation of an initial population. It can provide sufficient diversity of individuals at the beginning of GA. Second, we adopted an inferior selection to choose the parents for the crossover and mutation operations. It helps to maintain exploitation capability throughout the evolution process. Third, we employed a modification of the hybrid scheduling algorithm to decode the chromosome of the individual into a schedule, which can generate an active and non-delay schedule. The experimental results show that our proposed algorithm is superior to the current best evolutionary algorithms at most benchmark problems.

• Journal of Arbitration Studies
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• v.23 no.2
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• pp.81-113
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• 2013

The World Trade Organization (WTO) offers remedies for non-compliance by the introduction of compensation or retaliation in the Dispute Settlement Understanding (DSU). There are no the provisions under the WTO DSU and it seems unclear what retaliation is attempting to achieve. Therefore, it is unclear whether the goal of WTO retaliation is to induce compliance or to restore the balance between the rights and the obligations of WTO members. It has been claimed the WTO has a strong dispute settlement system by providing retaliation when the recommendations and rulings of Dispute Settlement Body (DSB) are not complied with. But this seems to be inadequate to bring about effective and timely compliance. Especially there is a problem with free riding by a violating member because the level of retaliation is determined from the expiration of a reasonable period of time, providing an incentive to delay compliance. Also the level of the suspension of concessions or other obligations authorized by the DSB is equivalent to the level of nullification or impairment, according to DSU Article 22.4. However, if the member concerned objections to the level of the suspension proposed, the matter shall be referred to arbitration. The arbitrator shall not examine the nature of the suspension of concessions or other obligations to be suspended but shall determine whether the level of such suspension is equivalent to the nullification or impairment. The arbitrator makes an assessment standard of equivalence by comparing the suspension of concessions or other obligations and the nullification or impairment calculated in terms of the amount of trade. But it is necessary that other standards replace the quantitative standards when the level of the nullification or impairment cannot be quantified by concrete damages.