• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.805-810
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• 2019

Recently, a majority of 4G mobile telecommunication manufacturers prefer repeaters with good adaptability. In this paper, we propose a new LMF(: Least Means Fourth) algorithm for LTE(: Long Term Evolution) RF(: Radio Frequency) Repeater. The proposed algorithm is a modification of the LMF, which appropriately adjusts the step size and improves performance according to the Sign function. The steady state MSE(: Mean Square Error) performance of the proposed LMF algorithm with step size of 0.009 is low level at about -25dB, and the proposed LMF algorithm requires 500 less iterations than the conventional algorithms at MSE of -25dB.

• Electronics and Telecommunications Trends
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• v.25 no.6
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• pp.29-37
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• 2010

본 논문에서는 무선망과 신호처리 기술의 발달과 1GHz급 이상의 고성능 모바일 장치의 등장에 따라 현재의 모바일 음성 서비스 품질과 확연히 차별화된 서비스를 제공하기 위해 3GPP에서 논의중인 EVS 코덱의 기술적 특성 및 최간 표준화 동향에 대해 기술한다. 3GPP에서는 지난 3월, 2년간의 논의를 거쳐 4G 모바일과 같은 EPS 시스템에서 차별화된 새로운 증감음성 품질의 서비스 제공이 필수적이라는 판단 하에 EVS 코덱 표준의 개발을 시작하였다. 현재 EVS 코덱 표준화를 위해 세부적인 가능과 성능 목표에 대해 협의를 진행중이며 표준의 완료 계획시점인 2012년 상반기경, 4G/LTE에서는 광대역 수준의 음성서비스에 비해 신호대역폭이 2배가 확장된 슈퍼와이드밴드급의 증감음성 서비스가 제공될 것으로 전망한다.

• ETRI Journal
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• v.38 no.4
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• pp.622-633
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• 2016

A discontinuous reception (DRX) operation is included in the Long Term Evolution (LTE) system to achieve power saving and prolonged battery life of the user equipment. An improvement in DRX power saving usually leads to a potential increase in the packet delay. An optimum DRX configuration depends on the current traffic, which is not easy to estimate accurately, particularly for non-real-time applications. In this paper, we propose a novel way to vary the DRX cycle length, avoiding a continuous estimation of the data traffic when only non-real-time applications are running with no active real-time applications. Because a small delay in non-real-time traffic does not essentially impact the user's experience adversely, we deliberately allow a limited amount of delay in our proposal to attain a significant improvement in power saving. Our proposal also improves the delay in service resumption after a long period of inactivity. We use a stochastic analysis assuming an M/G/1 queue to validate this improvement.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.118-123
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• 2022

We implemented a real-time cloud robotics application by offloading robot navigation engine over to 5G Mobile Edge Computing (MEC) sever. We also ran a fleet management system (FMS) in the server and controlled the movements of multiple robots at the same time. The mobile robots under the test were connected to the server through 5G SA network. Public 5G network, which is already commercialized, has been temporarily modified to support this validation by the network operator. Robot engines are containerized based on micro-service architecture and have been deployed using Kubernetes - a container orchestration tool. We successfully demonstrated that mobile robots are able to avoid obstacles in real-time when the engines are remotely running in 5G MEC server. Test results are compared with 5G Public Cloud and 4G (LTE) Public Cloud as well.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.120-124
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• 2017

This paper describes the product of search and rescue system with dynamic model. This spread spectrum system based new standard of COSPAS-SARSAT is results of RF signal generation and transmission. we will test performance evaluation which implement signal process adapting Dynamic model and we will adapt the CAF model using TDOA and FDOA relationship.

• ETRI Journal
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• v.38 no.3
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• pp.463-468
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• 2016

With the constant increase in network traffic, wireless operators are finding it more challenging to keep network hardware costs to a minimum. At the same time, the energy cost associated with operating a network has increased proportionally. Therefore, the search for higher network capacity is simultaneously accompanied by the search for a cost-efficient network deployment. In this paper, we show that a saving in transmitted signal energy can be achieved at the signal design level by deploying very specific signal processing techniques. Using an orthogonal frequency-division multiplexing signal for Long-Term Evolution networks as an example, we utilize a novel non-uniform companding quantizer to save a transmitted signal energy. Our results show that by using non-uniform quantization it is possible to further optimize 4G wireless networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.900-902
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• 2013

In this paper, we propose the CPW antenna with three folded lines for miniaturization. This antenna is consisted of a meander-line on the middle position for LTE band and two folded lines. As widths of three lines are gradually changed to broaden bandwidth, antenna is designed.

• Journal of Digital Convergence
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• v.11 no.8
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• pp.359-365
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• 2013

Companies recently tend to move their business sites to a customer-centered location and the work place is changed from specific time and place to a working environment of anytime and anywhere the job can be done. Therefore, the design and implementation of business-work management system using mobile applications has been actively researched. In this study, the business-work management system, a mobile application using GPS, is immediately transmitted to ERP system and is stored into a company's formula DB, at such sites outside the company as business trip destinations, training institutions, and outside meetings, through smartphone-based GPS location information using WiFi, 3G, LTE, or 4G. In this way, it is aimed to design and develop the mobile application system to obtain rapid authorization in connection with electro nic document approval system. Also, this study is to measure the system's productivity and expected effects through the users' survey results by actual application of the designed and developed system to companies.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.469-478
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• 2022

This paper contains the results of developing smart devices and applications to monitor the load power of the industrial manufacturing machine and evaluate its performance. The smart devices in this paper are divided into two functionalities, which are collecting load power along with operating environment data of industrial manufacturing machines and transmitting the data to servers. Load power data collected from the smart devices are uploaded to MariaDB inside the Amazon Web Service (AWS) server. Using the RESTFul API, the uploaded power data can be retrieved and shown on the web and mobile application in the form of a graph to provide monitoring capability. To evaluate the performance of the developed system, the response time from MariaDB to web and mobile applications was measured. The results is ranging from 0.0256 to 0.0545 seconds in a 4G (LTE) network environment and from 0.6126 to 1.2978 seconds in a 3G network environment, which is considered a satisfactory result.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5458-5464
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• 2012

In LTE-Advanced that different networks coexist, it is considered that it is actually difficult to provide service continuity with a procedural and static control method applied to the existing voice service. This research suggests a resource management framework to support the service continuity effectively based on QoS support. In other words, as context information of mobile terminal and base station changes, set-up of related functions such as ISHO, cell selection, source allocation, load control, and QoS mapping is adapted; each function fits into the change, exchanges the process of reorganization, and interacts; these actions go toward to satisfy service continuity. For this aim, the sequence diagram between the function modules for supporting four kind of ISHO is described and then a scenario for ISHO is considered.