• 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.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1997.11a
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• pp.241-247
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• 1997

통신망의 발전과 컴퓨터를 통한 멀티미디어 처리 기술의 발달로 인해 사용자들은 보다 나은 서비스를 원하게 되었다. 이로 인해 컴퓨터 통신망에서 다양한 분산 멀티미디어 응용을 실현하기 위한 연구가 활발하게 진행되고 있으며, 그 대표적인 응용으로 화상회의가 있다. 그러나 멀티미디어 데이터를 다루는 응용들은 몇 가지 어려운 문제가 있으며 그 중의 하나가 멀티미디어 데이터의 동기화(synchronization) 문제이다. 멀티미디어 동기화의 관련된 기존의 연구들은 특정 조건하에서는 잘 수행되지만 다른 환경에서는 한계를 나타내는 문제점을 보이고 있다. 본 논문에서는 응용의 동기화 요구사항과 사용자의 인지적 특성에 의해 유연한 동기화 서비스를 제공하는 새로운 동기화 기법을 제안한다. 본 기법은 유동적인 망환경의 변화에 적응적이고 시계속도 차이가 있는 시스템 환경에서도 영향을 받지 않는 동기화방식이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.83-86
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• 2012

최근 임베디드 시스템이 이용되는 이동체나 자동화 공장에서 각 디바이스들간의 분배된 작업이 정확한 시간에 맞추어 작동 할 것을 요구하고 있어 시간 동기화는 중요하게 인식되고 있다. 각각의 시스템은 자기의 시계를 가지고 처리되기 때문에 이들간의 시간 정보의 오차를 적게 하여야 한다. 이에 본 논문에서는 SNTP 프로토콜을 이용해 타임서버로부터 시간의 단위를 정하여 단위 간격마다 시간을 여러 번 확인하여 오차를 조정하고, 실험을 통해 평균오차와 최대오차를 구하여 시간 동기화 시점을 확인하였다. 이를 통해 시간 동기화 시점을 미리 조정하여 다음 장치들 간의 통신 시점에서 동기화를 할 경우 오차를 줄이는 방법을 제안한다. 본 논문에서 제안한 방법을 Rabbit Board 6700 으로 구현하고 검증하여 이를 시간적 정밀함이 요구되는 응용분야에 적용할 수 있게 한다.

• Proceedings of the Korea Society for Simulation Conference
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• 1995.04a
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• pp.0-0
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• 1995

대부분의 시뮬레이션이 특정 시스템의 모델에 대한 분석을 위해 시행된다. 하지만 이러한 용도뿐만 아니라 실제 시스템이 의도대로 진행될 것인지의 검증을 위해서 시뮬레이 션을 사용할 수 있다. 예를 들어, FMS(유연생산시스템)와 같이 분산된 환경에서 작동하는 시스템을 구축하는 경우, 시스템의 작동 여부를 검증하는 용도로 시뮬레이션을 사용할 수 있는데 이 경우 첫단계에는 모든 기계를 시뮬레이션으로 대치하여 처리하다가 한단위씩 실 제 기계로 교환하여 목적에 부합하는지를 검토함으로써 전체 시스템을 용이하게 구축할 수 있다. 위와 같은 경우 그 실행 과정에서 실제 작업과 시뮬레이션 작업이 혼합되어 나타나게 된다. 이러한 혼합 분산 시뮬레이션에서는 실제 작업과 시뮬레이션 작업을 동기화하는 문제 가 발생하며 하드웨어의 실제 작업뿐만 아니라 소프트웨어의 실작업 시간 또는 시뮬레이션 진행에 반영되어야만 한다. 여기서는 실제 작업과 시뮬레이션 작업이 혼합되어 나타나는 혼 합 분산 시뮬레이션을 정의하고, 그 필요성을 살펴본다. 그리고 이러한 문제에 대한 기존의 시뮬레이션 연구들의 적용성을 고찰해 보며, 혼합 분산 시뮬레이션의 운영 방법으로서 중앙 시계를 이용한 실제 작업과 시뮬레이션 작업의 동기화 방안을 제시한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.1
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• pp.91-96
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• 2012

Recently, the research of security and its related problems has been received great interested. The research for hper-chaos systems and its synchronization are actively processing as one of method to apply to secure and cryptography communication. In this paper, we propose the synchronization method by coupling coefficient of linear and nonlinear in order to accomplish the synchronization of hyper-chaos system that organized by SC-CNN(State-Controlled Cellular Neural Network). We also verify and confirm the result of synchronization between entire transmitter and receiver, and each subsystem in transmitter and receiver through the phase portrait and difference of time-series by the computer simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.313-318
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• 1999

A number of recent paper have investigated the feasibility of synchronizing chaotic system. In this paper we proposed the chaotic synchronization of the canonical Chua's circuit with RLCG transmission line by drive-response system. We expected that to be available to apply this secure communication with RLCG transmission line.

• Journal of Broadcast Engineering
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• v.23 no.2
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• pp.197-205
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• 2018

Panoramic image is one of the technologies that are commonly used today. However, technical difficulties still exist in panoramic video production. Without a special camera such as a 360-degree camera, making panoramic video becomes more difficult. In order to make a panoramic video, it is necessary to synchronize the timeline of multiple videos shot at multiple locations. However, the timeline synchronization method using the internal clock of the camera may cause an error due to the difference of the internal hardware. In order to solve this problem, timeline synchronization between multiple videos using visual information or auditory information has been studied. However, there is a problem in accuracy and processing time when using video information, and there is a problem in that, when using audio information, there is no synchronization when there is sensitivity to noise or there is no melody. Therefore, in this paper, we propose a timeline synchronization method between multiple video using audio waveform. It shows higher synchronization accuracy and temporal efficiency than the video information based time synchronization method.

• Korean Journal of Cognitive Science
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• v.27 no.4
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• pp.501-539
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• 2016

The human mind is a self-evolving system that develops along a multidimensional hierarchical pathway in response to traumatic stimulus. In absence of trauma, a mind integrated in conflict-free state is called monistic. When the monistic mind responses to a traumatic stimulus, a response polarity forms toward stimulus polarity within the mind, turning it into a bipartite structure. Dialectical interaction between the two opposites, originating from their incompatibility, creates a new third polarity in the upper dimension. Thereby, the mind turns into a trinity structure. When the interaction among the three polarities becomes optimized, the plasticity of the mind gets maximized into the "far-from-equilibrium state," and the function of three polarities is synchronized. Through this recalibration, the mind returns back to its monistic structure. If the mind with the recurred monistic structure responds to another traumatic stimulus, this cycle of hierarchical transformation repeats itself in this cyclical and fractal growth process through synchronization of basic trinity system. Applying this concept to the process of post-traumatic growth (PTG), this paper explores how the mind transforms traumatic experiences into PTG and proposes a 'PTG Clock' that shows a fundamental sequence in the development of the human mind. The PTG Clock consists of seven hierarchical phases, and each of the first six phases has two opposite sub-phases: shocked/numbed, feared/intrusive, paranoid/avoidant, obsessional/explosive, dependent/depressive, and meaningless/searching for meaning. The seventh, the synchronization phase, completes one cycle of the mind's transformation, realizing a grand trinity system, where the mind synchronizes its biological, social, and existential dimensions. At that point, the mind becomes more susceptible to not only the stimulus of its own traumatic experience but also the pain of others. Thereby, the PTG Clock sets out on a journey to another cycle of transformation in higher dimensions. The validity of this transformational process for the PTG Clock will be examined by comparing it to Horowitz's theory of stress response syndrome.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.4
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• pp.285-293
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• 2020

In this paper, to improve Synthetic Aperture Radar (SAR) image quality, the effect of time synchronization error in the EGI/IMU (Embedded GPS/INS, Inertial Measurement Unit) integrated system is analyzed and state augmentation is applied to compensate it. EGI/IMU integrated system is widely used as a SAR motion measurement algorithm, which consists of EGI mounted to obtain the trajectory and IMU mounted on the SAR antenna. In an EGI/IMU integrated system, a time synchronization error occurs when the clocks of the sensors are not synchronized. Analysis of the effect of time synchronization error on navigation solutions and SAR images confirmed that the time synchronization error deteriorates SAR image quality. The state augmentation is applied to compensate for this and as a result, the SAR image quality does not decrease. In addition, by analyzing the performance and the observability of the time synchronization error according to the maneuver, it was confirmed that the time-variant maneuver such as rotational motion is necessary to estimate the time synchronization error adequately. In order to reduce the influence of the time synchronization error on the SAR image, the time synchronization error must be compensated by performing maneuver changing over time such as a rotation before SAR operation.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.3 no.1
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• pp.17-29
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• 1999

The reliable authentication of a communicating party and a network component is an essential factor to achieve the security in a computer network. The Kerberos Authentication Services has been the most successful solution which is widely used today but its requirement for synchronized clocks has been a serious limitation to use it. In this paper we presented an extended Kerberos method which avoids the synchronization requirement for a single-time ticket user. We modified the Kerberos protocol minimally by replacing the synchronization requirement with the challenge-response method.