• Smart Media Journal
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• v.7 no.4
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• pp.17-23
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• 2018

We proposed a LSTM-based RNN model that can effectively perform the automatic spacing characteristics. For those long or noisy sentences which are known to be difficult to handle within Neural Network Learning, we defined a proper input data format and decoding data format, and added dropout, bidirectional multi-layer LSTM, layer normalization, and attention mechanism to improve the performance. Despite of the fact that Sejong corpus contains some spacing errors, a noise-robust learning model developed in this study with no overfitting through a dropout method helped training and returned meaningful results of Korean word spacing and its patterns. The experimental results showed that the performance of LSTM sequence-to-sequence model is 0.94 in F1-measure, which is better than the rule-based deep-learning method of GRU-CRF.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.20-29
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• 2014

Recently, LTE is preparing to make a new leap forward LTE-A all over the world. As LTE privides high speed service, the role of mobile phones seems to change from voice to data service. According to Cisco, global mobile data traffic will increase nearly 11-fold between 2013 and 2018. Mobile video traffic will reach 75% by 2018 from 66% in 2013 in Korea. However, voice service is still the most important role of mobile phones. Thus, controllability of throughput and low BLER is indispensable for high-quality VoIP service among various type of traffic. Although the maximum AMR-WB, 23.85 Kbps is sufficient to a VoIP call, it is difficult for the LTE which can provide tens to hundreds of MB/s may not keep the certain level VoIP QoS especially in the cell-edge area. This paper proposes a new scheduling algorithm in order to improve VoIP performance after analyzing various scheduling algorithms. The proposal is the technology which applies more priority processing for VoIP than other applications in cell-edge area based on two-tier scheduling algorithm. The simulation result shows the improvement of VoIP performance in the view point of throughput and BLER.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1299-1302
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• 2001

인터넷의 폭발적인 증가와 다양한 무선 서비스에 대한 수요 증가에 따라 용량이 크고, 데이터 전송 속도가 빠르며, 멀티미디어를 지원 할 수 있는 무선 인터넷 서비스가 필요하게 되었다. 또한 증가하는 사용자수를 수용하기 위해서 마이크로/피코 셀(micro/pico cell)을 도입하게 되었고, 이로 인하여 빈번한 핸드오프가 발생하게 되었다[1,2]. 이를 해결하기 위해서 MRSVP(Mobile Resource reservation protocol)와 같은 무선 자원예약 프로토콜이 제안되어지고 있다(4). 제안된 MRSVP 에서는 자원예약 지역의 불명확성과 지나친 신호부하를 초래하게 되었고, 이를 해결하기 위해서 본 논문에서는 계층적 MRSVP(H-MRSVP)를 이용한 새로운 호 제어기법과 무선 자원 예약 기법에 대해 연구하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.4 s.334
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• pp.21-28
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• 2005

SC-FDE (Single Carrier with Frequency-Domain Equalization), one of physical layers of IEEE802.16, is less sensitive to nonlinear power amplifiers than OFDM while its complexity and performance is comparable. The guard interval length in SC-FDE should be greater than the maximal delay spread. While a delay spread is small in most wireless communication environments, a very large delay spread can be possibly encountered in the mountain areas or due to the repeaters. This paper proposes SC-FDE with variable-length guard intervals. In the proposed method the guard interval length can be determined per each cell or per each subscriber stations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.395-402
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• 2003

The capacity of a CDMA cellular system is determined by the amount of interference, therefore the exact estimation of interference is important to evaluate the system performance. In this paper, we propose an approximated equation which calculates reverse link other cell interference in the CDMA cellular systems. The equation using Riemann-Zeta function has a property that it is useful in case of any radio propagation loss exponents. And we compare calculation results with simulation results in other to verify it's usefulness. The upper bound of system capacity calculated with the proposed approximated equation gives almost alike result with the simulation. The proposed interference bound is useful to calculate system capacity and to evaluate some algorithm in a hierarchical cellular system which must be considered various propagation exponents.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.11
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• pp.2862-2868
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• 1996

A sueueing model is developed and analyzed to evaluate the performance of a local and a remote destination of one multicast connection subject to a simple two-level(binary) feedback-based adaptive rate control scheme. The reate control scheme is a simple extension of the one for point-to-point case. Individual cell loss probabilities at the local and remote destinations are obtained to study the fairness of the adaptive rate control scheme. Numerical results show that this simple adaptive rate control scheme, which is fair when it is applied to a multicast connection consisting of destinations with equal propagation delays, bears bias against remote destination.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.589-594
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• 1991

Group Technology (GT) is a technique for identifying and bringing together related or similar components in a production process in order to take advantage of their similarities by making use of, for example, the inherent economies of flow production methods. The process of identification, from large variety and total of components, of the part families requiring similar manufacturing operations and forming the associated groups of machines is referred as 'machine-component grouping'. First part of this paper is devoted to describing a hierarchical divisive algorithm based on graph theory to find the natural part families. The objective is to form components into part families such that the degree of inter-relations is high among components within the same part family and low between components of different part families. Second part of this paper focuses on establishing cell design procedures. The aim is to create cells in which the most expensive and important machines-called key machine - have a reasonably high utilization and the machines should be allocated to minimize the intercell movement of machine loads. To fulfil the above objectives, 0-1 integer programming model is developed and the solution procedures are found. Next an attempt is made to test the feasibility of the proposed method. Several different problems appearing in the literature are chosen and the results air briefly showed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.3
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• pp.285-297
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• 2016

In this paper, a centralized mmWave-based multi-spot beam cellular system architecture having such a base station equipped with a plurality of beam-forming antennas, multi-layered dynamic cell configuration method as one of key concepts of this system operation and a mobility management method based on it are introduced. To estimate the performance of new system, system simulation was performed under the ideal environment without blockage. These results show the possibility that system capacity can be dramatically increased and mobility performance similar to the existing cellular system may be achieved.

• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.151-159
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• 2008

Mobile broadband wireless network is emerging as one of the hottest research areas due to technical advances, and the demands of users who wish to enjoy the same network experience on the move. In this paper, we investigate the handover process at the medium access control (MAC) layer in an IEEE 802.16e-based system. In particular, we identify problems concerned with the scan initiation Process called cell reselection and propose a received signal strength (RSS) estimation scheme to dynamically trigger a scanning process. We show how the RSS estimation scheme can timely initiate a scanning process by anticipating RSS values considering scan duration required.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.4
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• pp.728-736
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• 2007

The more improved the Internet and the information technology, the stronger cryptographic system is required which can satisfy the information security on the platform of personal hand-held devices or smart card system. This paper introduces a case study of designing an elliptic curve cryptographic processor of a high performance that can be suitably used in a wireless communicating device or in an embedded system. To design an efficient cryptographic system, we first analyzed the operation hierarchy of the elliptic curve cryptographic system and then implemented the system by adopting a serial cell multiplier and modified Euclid divider. Simulation result shows that the system was correctly designed and it can compute thousands of operations per a secdond.