• Title/Summary/Keyword: Time synchronization

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Time Delay Error Analysis and Compensation Method of Integrated Navigation System for Aircraft Store (항공장착물의 전달정렬을 위한 통합항법장치 시간 지연 오차 분석 및 보상 기법)

  • Seo, Byung-Il
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.7
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    • pp.592-601
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    • 2018
  • The GPS/INS integrated navigation system, which is one of the electronic equipments mounted on military aircraft store, can not directly receive GPS signals by the aircraft wing before the drop, so GPS navigation data is received from the aircraft and used for filter integration, afterwards, the integrated navigation is performed using the GPS information directly received through the antenna. In this case, it is possible to operate the mount in old aircraft without any modification of the aircraft when GPS data is transmitted using wireless. However, the delay occurs while the aircraft navigation data is transmitted to the integrated navigation filter of the aircraft store via wireless, which affects the time synchronization of the GPS measurement and the INS information, affecting the integrated navigation performance. In this paper, an algorithm to analyze and compensate the effect of generation and transmission delay that can occur when implementing GPS/INS integrated navigation system of aircraft store that receives GPS data via wireless.

Evaluation of EtherCAT Clock Synchronization in Distributed Control Systems (분산 제어 시스템을 위한 EtherCAT 시계 동기화의 성능 평가)

  • Kim, Woonggy;Sung, Minyoung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.7
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    • pp.785-797
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    • 2014
  • Support for the precise time synchronization of EtherCAT, known as distributed clock (DC), enables the design of highly synchronized operations in distributed real-time systems. This study evaluates the performance of the EtherCAT DC through extensive experiments in a real automation system. We constructed an EtherCAT control system using Xenomai and IgH EtherCAT stack, and analyzed the clock deviation for different devices in the network. The results of the evaluation revealed that the accuracy of the synchronized clock is affected by several factors such as the number of slave devices, period of drift compensation, and type of system time base. In particular, we found that careful decision regarding the system time base is required because it has a fundamental effect on the master operation, which results in significantly different performance characteristics.

Development of Integrated Navigation Computer for On/Off Line Processing (실시간/후처리 기법을 고려한 복합 항법 컴퓨터 개발)

  • Jin, Yong;Park, Chan-Gook
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.8
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    • pp.133-140
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    • 2002
  • In this paper, the structure of integrated navigation computer for experiment is proposed. It is designed for considering the real time processing and data storage capacity. It will be used in missile, aircraft, submarine system and experimental vehicle. The I/O device supports IMU, GPS, odometer, altimeter, depth sensor, inclinometer etc. And the main storage device uses the tape device. That can improve the system stability. Therefore it can be used in a high dynamic or shock environment. The embedded linux is used as an Operating System. For the real time capability, sensor data processing and algorithm processing units are seperated. The time synchronization is referenced by IMU data.

A Method of the Grandmaster Selection and the Time Synchronization Using Single TimeSync Frame for Audio/Video Bridging (동기식 이더넷에서 단일 타임싱크 프레임을 이용한 그랜드마스터 결정 및 시간 동기 방법)

  • Kang, Sung-Hwan;Lee, Jung-Won;Kim, Min-Jun;Eom, Jong-Hoon;Kwon, Yong-Sik;Kim, Sung-Ho
    • Journal of KIISE:Information Networking
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    • v.35 no.2
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    • pp.112-119
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    • 2008
  • Today, A matter of concern of home network technology increase. The standard of communication between home network devices are required. IEEE 802.1 AVB(Audio/Video Bridging) specifies transmission method for time-sensitive data between these devices using Ethernet in bridged local area networks. IEEE 802.1 AVB and IEEE 1588 PTP(Precision Time Protocol) have various message type for grandmaster selection and synchronize the devices. These messages bring on complexity protocol. We propose a method that uses Single TimeSync frame in order to the problem. Our proposal is appropriate process complexity and low transmission delay for home network by using the TimeSync frame. Furthermore, after all devices are adjusted to the single TimeSync frame, a resource reservation, a forwarding and queueing rule are needed for a time-sensitive application.

A Study on the Noise Emission Characteristics of Turbo Axial Flow Fan by Experimental Method (터보형송풍기의 소음 방사특성에 관한 실험적 연구)

  • 김동규;백종진
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2003.10a
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    • pp.271-277
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    • 2003
  • Recently as the environmental noise getting influential social problem, it is the fact that the demand on noise reduction increases with the advance of the standard of living. Therefore increasing the interest on the noise in common, it is eagerly demanded that the endeavour for reducing the noise of the rotating machinery, especially the machinery related a flowing including the household electric products, which is pointed out the primary noise source in environment. As proceeding study for fan noise, theory of fan noise property is arranged and this control method is shown. Blade passage noise of total noise spectrum. Thus in the aspect of noise reduction, noise source and identification of noise radiation characteristics of axial flow fan are demanded in detail. The sound source is analyzed by using sound pressure and sound intensity. In that time, synchronization of axial flow fan using optical sensor is executed, and to identify the location of exact noise source in the fan profile determination of recording time is proposed. In the rotating of tan, it is explained that the location of noise source exists in and by the directivity, the noise radiation pattern of axial flow fan is determined and the flow of sound is visualized in the figure of contour mapping.

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Indoor Positioning System Using Ultrasonic and RF (초음파와 RF를 이용한 실내 측위 시스템)

  • Zho, Back-doo;Kwon, Sung-oh;Cheon, Seong-eun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.2
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    • pp.413-423
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    • 2017
  • In this paper, we propose a ultrasonic and RF-based indoor localization system. In previous work, various systems were proposed for indoor localization, but they have limitation in applicability due to time-synchronization, complexity, or accuracy. To overcome such problems, an indoor localization system with ultrasonic and RF is proposed. A transmitting system is composed of a pair of ultrasonic and RF transmitters and the receiving system is composed of multiple ultrasonic receivers and one RF receiver. The theoretical performance limitation is also analyzed. To verify localization performance, we have implemented a receiving systems and a transmitting system using Arduino modules. Experiments were performed in $2m{\times}2m{\times}2m$ space and the localization errors had a mean of 6.1cm and a standard deviation of 1.6cm.

A Study on Conversion Between UML and Source Code Based on RTT(Round-Trip Translator) (RTT(Round-Trip Translator) 기반의 UML과 소스코드 변환에 대한 연구)

  • Kim, Ji Yong;Cho, Han Joo;Kim, Young Jong
    • KIPS Transactions on Software and Data Engineering
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    • v.8 no.9
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    • pp.349-354
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    • 2019
  • s programming education becomes more important in recent years, it is necessary to learn how the source code written by students reflects Object-Oriented(OO) concepts. We present a tool called the Round-Trip Translator(RTT) that transforms the Unified Modeling Language(UML) class diagram and Java source code to provide a web-based environment that provides real-time synchronization of UML and source code. RTT was created by improving existing RTE and is a tool for students who are learning OO concepts to understand how their UML or source code reflects the concepts that user intended. This study compares the efficiency and user- friendliness of RTT with the existing Round-Trip Engineering-based tools. The results show that students have improved understanding of OO concepts through UML and source code translation by using the RTT. We also found out that students were satisfied with the use of the RTT, which provides more efficient and convenient user interface than the existing tools.

A Real-time Virtual Model Synchronization Algorithm Using Object Feature Detection (객체 특징 탐색을 이용한 실시간 가상 모델 동기화 알고리즘)

  • Lee, Ki-Hyeok;Kim, Mu-In;Kim, Min-Jae;Choi, Myung-Ryul
    • Journal of Digital Convergence
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    • v.17 no.1
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    • pp.203-208
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    • 2019
  • In this paper, we propose a real-time virtual model synchronization algorithm using object feature detection. The proposed algorithm may be useful to synchronize between real objects and their corresponding virtual models through object feature search in two-dimensional images. It consists of an algorithm to classify objects with colors individually, and an algorithm to analyze the orientation of objects with angles. We can synchronize the motion of the real object with the virtual model by providing the environment of moving the virtual object through the hand without specific controllers. The future research will include the algorithm to synchronize real object with unspecified shapes, colors, and directions to the corresponding virtual object.

Digital Twin Model Design And Implementation Using UBS Process Data (UBS공정 데이터를 활용한 디지털트윈 모델 설계 및 구현)

  • Park, Seon-Hui;Bae, Jong-Hwan;Ko, Ho-Jeong
    • Journal of Internet of Things and Convergence
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    • v.8 no.3
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    • pp.63-68
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    • 2022
  • Due to COVID-19, many paradigm shifts in existing manufacturing facilities and the expansion of non-face-to-face services are accelerating worldwide. A representative technology is digital twin technology. Such digital twin technology, which existed only conceptually in the past, has recently become feasible with the construction of a 5G-based network. Accordingly, this paper designed and implemented a part of the USB process to enable digital twins based on OPC UA communication, which is a standard interlocking structure, between real object objects and virtual reality-based USB process in accordance with this paradigm change. By reflecting the physical characteristics of real objects together, it is possible to simulate real-time synchronization of these with real objects. In the future, this can be applied to various industrial fields, and it is expected that it will be possible to reduce costs for decision-making and prevent dangerous accidents.

Analysis on Mapping Accuracy of a Drone Composite Sensor: Focusing on Pre-calibration According to the Circumstances of Data Acquisition Area (드론 탑재 복합센서의 매핑 정확도 분석: 데이터 취득 환경에 따른 사전 캘리브레이션 여부를 중심으로)

  • Jeon, Ilseo;Ham, Sangwoo;Lee, Impyeong
    • Korean Journal of Remote Sensing
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    • v.37 no.3
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    • pp.577-589
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    • 2021
  • Drone mapping systems can be applied to many fields such as disaster damage investigation, environmental monitoring, and construction process monitoring. To integrate individual sensors attached to a drone, it was essential to undergo complicated procedures including time synchronization. Recently, a variety of composite sensors are released which consist of visual sensors and GPS/INS. Composite sensors integrate multi-sensory data internally, and they provide geotagged image files to users. Therefore, to use composite sensors in drone mapping systems, mapping accuracies from composite sensors should be examined. In this study, we analyzed the mapping accuracies of a composite sensor, focusing on the data acquisition area and pre-calibration effect. In the first experiment, we analyzed how mapping accuracy varies with the number of ground control points. When 2 GCPs were used for mapping, the total RMSE has been reduced by 40 cm from more than 1 m to about 60 cm. In the second experiment, we assessed mapping accuracies based on whether pre-calibration is conducted or not. Using a few ground control points showed the pre-calibration does not affect mapping accuracies. The formation of weak geometry of the image sequences has resulted that pre-calibration can be essential to decrease possible mapping errors. In the absence of ground control points, pre-calibration also can improve mapping errors. Based on this study, we expect future drone mapping systems using composite sensors will contribute to streamlining a survey and calibration process depending on the data acquisition circumstances.