• ETRI Journal
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• 제38권6호
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• pp.1064-1073
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• 2016

An adaptive speech streaming method to improve the perceived speech quality of a software-based multipoint control unit (SW-based MCU) over IP networks is proposed. First, the proposed method predicts whether the speech packet to be transmitted is lost. To this end, the proposed method learns the pattern of packet losses in the IP network, and then predicts the loss of the packet to be transmitted over that IP network. The proposed method classifies the speech signal into different classes of silence, unvoiced, speech onset, or voiced frame. Based on the results of packet loss prediction and speech classification, the proposed method determines the proper amount and bitrate of redundant speech data (RSD) that are sent with primary speech data (PSD) in order to assist the speech decoder to restore the speech signals of lost packets. Specifically, when a packet is predicted to be lost, the amount and bitrate of the RSD must be increased through a reduction in the bitrate of the PSD. The effectiveness of the proposed method for learning the packet loss pattern and assigning a different speech coding rate is then demonstrated using a support vector machine and adaptive multirate-narrowband, respectively. The results show that as compared with conventional methods that restore lost speech signals, the proposed method remarkably improves the perceived speech quality of an SW-based MCU under various packet loss conditions in an IP network.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.550-552
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• 1995

Real time informations from industrial power system in operation can be used for efficient energy conservation, optimal operation of electrical equipments, and expansion planning of apparatus. Requirements for energy conservation and supplied power quality in customers are increasing significantly because of their effects on the production cost and efficiency. Thus, the development of low cost power management system which can can operate in domestic power system properly is substantially requested. In this research, operation software for real time monitoring and control system in customer power system has been developed to achieve the above purposes. The development of the operating software and related technologies are expected to be applied successfully for reducing electricity cost, enhancing power quality, determining facility expansion planning, operating optimal power system, increasing production efficiency, and reducing maintenance cost.

• 드라이브 ㆍ 컨트롤
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• 제14권4호
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• pp.29-36
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• 2017

Electronic control technologies that have long been developed for passenger cars spread to construction equipment and agricultural vehicles because of its outstanding performance achieved by embedded software. Especially, system program of transmission control unit (TCU) plays a crucial role for the superb shift quality, driving performance and fuel efficiency, etc. Since the control algorithm is embedded in software that is rarely analyzed, development of such a TCU cannot be conducted by conventional reverse engineering. Transmission simulator is a kind of electronic device that simulates the electric signals including driver operation command and output of various sensors installed in transmission. Standalone TCU can be run in normal operation mode with the signals provided by transmission simulator. In this research, transmission simulator for the tracked vehicle TCU is developed for the analysis of shift control algorithm from the experiments with standalone TCU. It was confirmed that shift experimental data for the simulator setup conditions can be used for the analysis of control algorithms on proportional solenoid valves and shift map.

• 소성∙가공
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• 제8권1호
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• pp.65-77
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• 1999

In recent years, the quality requirements from the customers of hot rolled steel strip have been steadily increasing in diversity and strictness. To meet these quality requirements as well as to improve productivity, steel mills have been doing their efforts for developing high performance Automatic Gauge Control (AGC) system. However, it is very time consuming and also needs a lot of money to develop the new technologies of AGC in actual mill. So, there has been a demand for developing the Dynamic Hot Rolling Simulator since late 80's. It is a kind of software packages and can analyze the dynamic behaviors of hot finishing rolling process without laborious experiments in actual mill. It can also be used as a designing tool of Automatic Gauge Controller. In this work, the Dynamic Hot Rolling Simulator which is applicable to 6 sands hot strip mill rolling was developed. The MATLAB with SIMLINK was used as a software developer for making the main part of simulator because it is very powerful tool for modeling, integrating, controller design, and simulation. In this paper, the structures and the mathematical models of the simulator were briefly described and the results of simulation on the transient phenomena of hot rolling process with actual mill data were also presented.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.544-558
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• 2013

This paper proposes a simplified and efficient control scheme for Unified Power Quality Conditioner (UPQC) based on three-level (NPC) inverter capable to mitigate source current harmonics and compensate all voltage disturbances perturbations such us, voltage sags, swells, unbalances and harmonics. The UPQC is designed by the integration of series and shunt active filters (AFs) sharing a common dc bus capacitor. The dc voltage is maintained constant using proportional integral voltage controller. The shunt and series AF are designed using a three-phase three-level (NPC) inverter. The synchronous reference frame (SRF) theory is used to get the reference signals for shunt and the power reactive theory (PQ) for a series APFs. The reference signals for the shunt and series APF are derived from the control algorithm and sensed signals are injected in tow controllers to generate switching signals for series and shunt APFs. The performance of proposed UPQC system is evaluated in terms of power factor correction and mitigation of voltage, current harmonics and all voltage disturbances compensation in three-phase, three-wire power system using MATLAB-Simulink software and SimPowerSystem Toolbox. The simulation results demonstrate that the proposed UPQC system can improve the power quality at the common connection point of the non-linear load.

• Journal of Welding and Joining
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• 제31권1호
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• pp.26-32
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• 2013

Recently, welding technology of nonferrous metals which were difficult to implement by arc welder has become available through digitalization of arc welding machine. Among them, the welding quality improvement of aluminum welding is very noticeable. These results increase the arc stability by controlling arc current and voltage waveform precisely, and control wire feed speed by synchronizing with arc current which the feed rate of filler wire is controlled by a precise motor control of servomotor and not by a simple constant speed feeding. Not only through the hardware digitalization of arc welding machine but also through advance of software of arc welding, it became possible to implement a certain level of welding quality by a simple operation. These led to CMT welding process implementation which requires low heat input than current arc welding and highly increased the applicability of the aluminum welding.

• 한국전자통신학회논문지
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• 제17권4호
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• pp.663-670
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• 2022

본 연구는 한국형 합동 전술데이터링크 체계 사업의 사례를 통해 무기체계 소프트웨어 개발 및 관리 매뉴얼에서 규정하고 있는 무기체계 소프트웨어 신뢰성 시험이 정의되기 전에 획득한 소프트웨어 자산을 안정적으로 무기체계에 통합하는 방안을 제시한다. 이를 위하여 무기체계 소프트웨어 신뢰성 시험에 대한 개요와 한국형 합동 전술데이터링크체계 사업의 특성에 따른 신뢰성시험 적용의 문제점을 기술하고, 각 문제점에 대한 사업의 결정안과 이를 통한 기대 효과를 기술한다.

• 융합신호처리학회논문지
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• 제11권2호
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• pp.169-176
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• 2010

Sag, Swell, Impulsive Transient, Harmonics 등의 비정상 전력품질 신호들은 산업체 전력전자 장비, 속도 조절 장치, 공정 제어 시스템의 운전에 상당히 나쁜 영향을 미쳐 전력 공급자 및 수용가 입장에서 매우 중요한 이슈가 되어왔다. 따라서 본 연구에서는 이상의 전력품질 신호들을 획득, 분석 및 인식하기 위하여 Matlab, Simulink, CCS 등의 소프트웨어와 TI의 TMS320C6713DSK 하드웨어 키트와 웨이블릿 변환과 신경 회로망 역전파 알고리즘을 사용하여 전력품질 인식 시스템을 구현하였다. 이 시스템의 실시간 인식 성능을 파악하기 위하여 SIL(Software In the Loop)와 PIL(Process In The Loop)를 수행하였고, 그 결과 평균 99%의 우수한 인식결과를 보여주었다.

• 한국멀티미디어학회논문지
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• 제14권12호
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• pp.1572-1582
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• 2011

The rapid growth of UnderWater Acoustic Sensor Networks (UW-ASNs) has led researchers to enhance underwater MAC protocols against limitations existing in underwater environment. We propose the customized robust real-time packet inspection mechanism with addressing the problem of the search for the data packet loss and network performance quality analysis in UW-ASNs, and describe our experiences using this approach. The goal of this work is to provide a framework to assess the network real-time performance quality. We propose a customized and adaptive mechanism to detect, monitor and analyze the data packets according to the MAC protocol standards in UW-ASNs. The packet analyzing method and software we propose is easy to implement, maintain, update and enhance. We take input stream as real data packets from sniffer node in capture mode and perform fully analysis. We were interested in developing software and hardware designed tool with the same capabilities which almost all terrestrial network packet sniffers have. Experimental results confirm that the best way to achieve maximum performance requires the most adaptive algorithm. In this paper, we present and offer the proposed packet analyzer, which can be effectively used for implementing underwater MAC protocols.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1271-1274
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• 1997

The industrial automation market encompasses all aspects of the discrete process in the manufactring industries. Nowadays many manufacturers are increasingly moving to increase plant capacity, and are trying to produce better quality at the lower costs. We have studied a modern projection-automation system to achieve the communication network which makes connection among all of the projection machines and connect them to a central computer. This communication system have to be very flexible and fast. Also we have studied the communication interface for the automatic production system including the hardware elements and the communication software.