• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.54-56
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• 1999

현재 많은 내장형 시스템을 구현하기 위한 방법론으로 가상 프로토타입(VP)을 이용하고 있다. 본 논문에서는 가상 프로토타입을 이용하여 내장형 시스템의 설계 및 구현을 위해 사용되는 시스템 명세 언어인 SpecCharts로 명세된 시스템을 동기적 의미론에 만족하는 SpecCharts의 Subset을 규명하여 동기화 형태로 해당명세를 변환시키고 이로부터 synchronous VHDL 코드로 생성할 수 있는 방법을 설계하였다. 동기적 의미론을 만족시키기 위하여 비결정적인 추상적인 모델(NDAM)을 이용하여 SpecCharts로부터 VHDL ？로 변환하는 방법을 제시하고, 변환된 VHDL 코드를 동기적 VHDL 코드로 변환하기 위하여 W. Baker에 의해 규명된 동기적 VHDL subset 적용하여 synchronous VHDL 코드를 생성하는 방법을 제안한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2052-2059
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• 2002

In this study, a synchronous controller algorithm being applicable to two-axis position synchronzation is developed. Based on coupling structure, the synchronous control system is composed of speed and synchronous controllers. The speed controller is designed to follow a speed reference. In addition, the synchronous controller is designed from the viewpoint of accurate synchronization and robust stability in H$\infty$ synthesis. Finally, the effectiveness of the presented controller is demonstrated through extensive experiments.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.2
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• pp.349-356
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• 2018

In this study, the synchronous control system is designed to restrain the speed difference generated between two propellers, namely, synchronous error in a dual electric propulsion system of unmanned surface vehicle, fish finder boat, etc. The control system based on coupling structure is composed of pre-filters and speed controllers for each propulsion system and a synchronous controller cross-coupled between two propulsion systems. The pre-filter and speed controller are designed in order that the propulsion system may follow the speed reference without overshoot and input saturation. And the synchronous controller is designed in consideration of damping and quickness of the synchronous controller system after analyzing effect of the skew disturbance and mismatched dynamic characteristics on synchronous error. Finally, the simulation results show that the designed control system is effective for elimination of synchronous error.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.842-854
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• 1997

In this paper, the improved Dual Leaky-Bucket(DLB) algorithm is proposed to reduce the synchronous cell loss rate. The conventional DLB algorithm does not support synchronous cells, but the proposed algorithm gives higher priority to synchronous cells. To reduce synchronous cell loss rate, the synchronous cell detector is used in the proposed algorithm. Synchronous cell detector detects synchronous cells, and passes them cells to the 2nd Leaky-Bucket. So it is similar to give higher priority to synchronous cells. In this paper, the proposed algorithm used audio/videl traffic modeled by On/Off and Two-state MMPP, and simulated by SLAM II package. As simulation results, the proposed algorithm gets lower synchronous cell loss rate than the conventional DLB algorithms. The improved DLB algorithm for multimedia synchronization can be extended to any other cells which require higher priority.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.57-67
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• 2021

This study explores what factors influence college students' synchronous online learning satisfaction and what advantages and disadvantages exist when it comes to taking synchronous online learning courses. In-depth interview results suggest that advantages of synchronous online learning are convenience (no need for travel, no limitation for study place), saving money, and no worry for contracting Corona 19. However, disadvantages of synchronous online learning are instability of online learning system, lack of interaction between learners and educators, difficulty of instant communication, low education quality, and unfairness of exams. This study found that college students taking synchronous online course think that synchronous online learning is more appropriate for theory-based course than practice-based courses in that theory-based courses are lecture-oriented while practice-based courses require interactivity between learners and educators. This study provides educators a baseline understanding on how college students think over synchronous online learning and how to enhance students' satisfaction with synchronous online learning.

• Journal of Power Electronics
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• v.10 no.5
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• pp.491-497
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• 2010

This paper proposes an estimation algorithm for the electrical parameters of synchronous reluctance motors (SynRMs) by using a synchronous PI current regulator at standstill. In reality, the electrical parameters are only measured or estimated in limited conditions without fully considering the effects of the switching devices, connecting wires, and magnetic saturation. As a result, the acquired electrical parameters are different from the real parameters of the motor drive system. In this paper, the effects of switching devices, connecting wires, and the magnetic saturation are considered by simultaneously using the short pulse and closed loop equations of resistance and synchronous inductances. Therefore, the proposed algorithm can be easily and safely implemented with a reduced measuring time. In addition, it does not need any external or additional measurement equipment, information on the motor's dimensions, and material characteristics as in the case of FEM. Several experimental results verify the effectiveness of the proposed algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1397-1402
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• 2010

While MOST is an in-vehicle network which transfers concurrently synchronous data, asynchronous data and control data, it provides high bandwidth synchronous section which can transfer video and audio without buffering. To transfer real time data using synchronous section, connections between source node and sink node, and channel allocation for connections are required. In this paper, we proposed synchronous data transfer method and channel allocation method by constructing MOST network after designing and implementing channel allocation module for using synchronous data section.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.253-256
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• 1997

This paper describes a novel design method for compensating field time-constant of micro-synchronous machine so that its terminal flux can show the same characteristics as large-scale synchronous machine's. In addition to it, the suggested design method can determine the field time-constant regulator's parameters considered the nonlinearities of micro-synchronous machine such as saturation and loading effect. This method applied to 5kVA micro-synchronous machine, and the digital time-constant regulator with digital AVR were designed such that the short field time-constant, $T_{do}'=1.12\;sec$, can take on the large-scale synchronous machine time constant, $T_{do}'=1.47\;sec$. After determining the parameters of controllers, the real time digital time-constant regulator and digital AVR algorithm were implemented by using the PC with Penumum processor, and the usefulness of suggested real time digital time-constant regulator was verified by observing its good performance on the excitation of micro-synchronous machine.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.59-64
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• 2019

Recently, time synchronous has become important for satellite launch control facilities, multiple thermal power plants, and power system facilities. Information from time synchronous at each of these industrial sites requires time synchronization to control or monitor the system with correlation. In this paper, IRIG-B codes, which can be used for time synchronous, are used as specifications in IRIG standard 200-16. Signals from IRIG-B120 (Analog), IRIG-B000 (Digital), and one PPS are output from GPS receiver. Using the signal from IRIG-B120 (Analog), it passes through the signal from the analog amplifier and generates one PPS signal using the field-programmable gate array. The FPGA is used cyclone EPM570T100I5N. According to IEEE regulations, the error of one PPS is specified within 1us, but in this paper, the error is within 100ns. The output of the one PPS signal was then compared and tested against the one PPS signal on the GPS receiver to verify accuracy and reliability. In addition, the proposed time synchronous is simple to construct and structure, easy to implement, and provides high time precision compared to typical time synchronous. The output of the one PPS signals and IRIG-B000 signal will be used in many industry sectors.

• 전기의세계
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• v.21 no.2
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• pp.20-24
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• 1972

The transient stability of the synchronous motor is generally improved by damper winding or flywheel. However the synchronous motor at full load will be pulled out from normal operation state when the period of power failure exceeds approximately ten cycle per second. This paper studies the method of improving the stability of synchronous motor by equipping the phase slipping switch between the motor and power source. This paper shows the motor does not pull out, which results from the decrease of power angle to about 30 electrical degrees by means of the switch even when the relatively long period of power failure brings the power angle to some 150 electrical degrees.