• Electronics and Telecommunications Trends
• /
• v.36 no.4
• /
• pp.34-47
• /
• 2021

To realize remote surgery from hundreds of kilometers away, a new communication environment with ultra-low latency and high-precision features is required. Thus, ultra-high precision networking technology that guarantees the maximum latency and jitter of end-to-end traffic on an Internet-scale wide area network is in development as part of 6G network research. This paper describes the current status of various networking technologies in ITU-T, ETSI, IEEE, and IETF to ensure ultra-low latency and high precision in wired networks.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.519-522
• /
• 2005

Decentralized Dynamic Surface Control(DDSC) for a class of nonlinear system interconnected via sensor network is presented in this paper. While a centralized design approach of DSC was developed in [1], the decentralized approach to deal with complex large-scale systems is proposed under the assumption that interconnected functions among subsystems are known via sensor network. As shown in [2], the separation principle for DDSC will allow us to design an estimation filter independently. Furthermore, the theoretical results are used to design and simulate an active vibration isolator under the assumption that many embedded sensors are distributed and communicate each other via wireless communication.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.34-34
• /
• 2004

정보의 급속한 발전, 컴퓨터, 가전기기, 자동차등 내구 소비재의 제품 개발기간 단축, 생산자의 지속적인 생산성 향상 활동, 소비자 선호의 다양성, 품질 요구 수준 상승 등 제반 환경변화는 절삭가공부분에 있어 핵심이 되고 있다. 여기에 전통적 제조업의 고부가가치화 및 새로운 시스템의 도입 등과 맞물려 최근의 초정밀 공작기계는 고속화, 고정밀화를 바탕으로 크게 발전하고 있다, 특히 21세기로 향하는 지금 공작기계 기술은 고속화, 정밀화, 개방화, 환경친화의 방향으로 혁신을 지속하고 있으며, 머지 않아 마이크로 프로세서의 급속한 발전에 힘입어 고속화 기술은 극 초고속화 단계로, 정밀화 기술은 극 초정밀화 단계로, CNC 기술은 오픈화 및 네트워크화를 통한 다양한 통신기술이 부가됨으로써 설계, 생산, 영업 및 서비스 정보와 연계시켜 통합제어를 통한 타 지역의 공작기계를 원격제어 할 수 있는 단계로 이르게 될 것이다.(중략)

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.5A
• /
• pp.561-570
• /
• 2008

Time synchronization is essential for a number of network applications such as high speed communication and parallel/distribution processing systems. As the era of ubiquitous computing is ushered in, the high precise time synchronization in wireless networks have been required in. This paper presents the design ana the implementation of the high precision time synchronization in wireless networks using ZigBee. To achieve high precision requirements, we have tried to analyze and reduce error factors such as the latency and jitters of a protocol stack on wireless environments. In addition, this paper includes some experiments and performance evaluations of our system. The result is that we established for nodes in a network to maintain their elects to within a 50 nanosecond offset from the reference clock.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.12A
• /
• pp.971-981
• /
• 2009

The coordination of distributed entities and events requires time synchronization. Precision time synchronization enables a variety of extensions of applications and provides much accurate information. The IEEE 1588 precision time protocol (PTP) provides a standard method to synchronize devices in a network. This paper deals with the design and implementation of a PTP gateway to extend IEEE 1588 to Zigbee networks. The PTP gateway can not only extend IEEE 1588 to Zigbee networks but also share the same time reference using IEEE 1588 between two or more Zigbee networks. This paper also presents experiments and performance evaluation of time synchronization using the PTP gateway. Our result established a method for nodes in a network to maintain their clocks to within a 300 nanosecond offset from the reference clock of a master node via Ethernet.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.1B
• /
• pp.86-97
• /
• 2009

RTLS is a system for automatically locating and tracking people and objects. The TDOA-based RTLS determines the location of the tag by calculating the time differences of a signal received from the tag. In TDOA-based RTLS, time synchronization is essential to calculate the time difference between readers. This paper presents a precision time synchronization method for TDOA-based RTLS over IEEE 802.15.4. In order to achieve precision time synchronization in IEEE 802.15.4 radio, we analyzed the error factors of delay and jitter. We also deal with the implementation of hardware assisted time stamping and the Kalman filtering method to minimize the error factors. In addition, this paper described the experiments and performance evaluation of the proposed precision time synchronization method in IEEE 802.15.4 radio. The results show that the nodes in a network can maintain their clocks to within 10 nanoseconds offset from the reference clock.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.47 no.5
• /
• pp.1-8
• /
• 2010

Clients require easy to use of product and operating and industry safety according to the change of a market and a factory. For overcoming it, this paper developed controller of take-out robots that take high speed and superprecision and supplement a week point as use the system based on network. development controller classify teaching pendant and center server PC. Center server PC service the information about all process to supervisor. Teaching pendant is the bridge that service various faculties such as control, user recognition, metallic pattern operation to the user using injection molding. The controller development for taking out injection molded body classify software and hardware. The development of software is divided into three step which is application program, user interface and device driver. the simple device driver is not classified and included in application program. The hardware induce the touch panel and wireless network and construct the effective process control and internet connection. The inject ion cycle of existing system was five second but advanced system has the inner four cycle, process efficiency and product operation through wireless network.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.1
• /
• pp.71-77
• /
• 2018

The optical time domain reflectometer (OTDR) is the most widely used method to monitor problems with currently installed optical fibers. The OTDR is an instrument designed to test the FTTx network and evaluates the physical properties of the fiber, such as transmission loss and connection loss. It is important to improve the spatial resolution in order to accurately grasp the optical path problems by using the OTDR. When the pulse width is less than twice the distance between the two reflectors, the signals reflected from the two reflectors are reflected without overlap, so that the reflected signal can be distinguished. However, when the pulse width is larger than twice the distance between the two reflectors, so that the reflected signal can not be distinguished. In order to overcome these limitations, this paper proposed a method of improving spatial resolution by applying a super resolution algorithm. As a result of the simulation, the resolution is improved when the super resolution algorithm is applied, and the event interval can be analyzed more precisely.

• Journal of the Korea Society for Simulation
• /
• v.31 no.1
• /
• pp.11-18
• /
• 2022

Recently, research to classify human activity using imagery has been actively conducted for the purpose of crime prevention and facility safety in public places and facilities. In order to improve the performance of human activity classification, most studies have applied deep learning based-transfer learning. However, despite the increase in the number of backbone network models that are the basis of deep learning as well as the diversification of architectures, research on finding a backbone network model suitable for the purpose of operation is insufficient due to the atmosphere of using a certain model. Thus, this study applies the transfer learning into recently developed deep learning backborn network models to build an intelligent system that classifies human activity using imagery. For this, 12 types of active and high-contact human activities based on sports, not basic human behaviors, were determined and 7,200 images were collected. After 20 epochs of transfer learning were equally applied to five backbone network models, we quantitatively analyzed them to find the best backbone network model for human activity classification in terms of learning process and resultant performance. As a result, XceptionNet model demonstrated 0.99 and 0.91 in training and validation accuracy, 0.96 and 0.91 in Top 2 accuracy and average precision, 1,566 sec in train process time and 260.4MB in model memory size. It was confirmed that the performance of XceptionNet was higher than that of other models.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.33 no.2
• /
• pp.131-142
• /
• 2015

In order to support the development of a cost-effective river bathymetric system, this research has focused on modeling GPS observables, which are obtained by array of five single-frequency receivers (i.e., two references and three rovers) to estimate the high accurate kinematic position, and the surveying vessel altitude. Also, by applying all GPS measurements as multiple-baselines with constraining rover baselines, we derived the socalled ‘kinematic network model.’ From the model, the integer-constrained least-squares (LS) for position estimation and the implicit LS for attitude determination were implemented, while a series of simulation tests with respect to the baseline lengths around 2km performed to demonstrate its accuracy analysis. The on-the-fly (OTF) ambiguity resolution tests revealed that ninety-nine percents of time-to-fix-first ambiguity (TTFF) can be decided in less than two seconds, when the positioning accuracy of ambiguity-fixed solutions was assessed as the greater than or equal to one and two centimeters in horizontal and vertical, respectively. Comparing to the GPS-derived attitudes, the achievable accuracy gradually descended in sequence of yaw, pitch and roll due to the antenna geometric configuration. Furthermore, the RMSE values for the baseline lengths of three to six meters were within ±1′for yaw, and less than ±10′and ±20′for pitch and roll, respectively, but those of between six to fifteen meters were less than ±1′for yaw, ±5′for pitch, and ±10′for roll.