• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.715-718
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• 2016

SpaceWire invented for on-board data handling in a spacecraft has Time-Code defined for time synchronization over SpaceWire network. Delay and jitter of the transmission of Time-Code caused when a Time-Code travels through a network are the main reasons of time synchronization error. This work proposes a scheme that can reduce the time synchronization error by using extended Time-Codes. The proposed scheme can remove both transmission jitter and transmission delay. The scheme will be validated in a simulation environment built with OMNeT++.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.497-500
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• 2010

Wireless sensor network is the system for data collection and data process between many nodes. For this work, Synchronization of operation execution and ordering many events are needed. Reference the external time information is the most accurate way to have same time information for all nodes but it's hard to apply these to sensor network. So there are many study of time synchronization there are many error occurred when the time synchronization is executed in the sensor network and minimizing these errors is important. In this paper, we propose how to minimize errors using several time stamp information exchanging when the network is initialized. When the big difference is occurred between receive time and send time in the node communication(cause of traffic overhead and etc), it shows big error of time correction and transfer delay time. but it's hard to detect these errors when it exchanges time stamp information just one time. so we try to reduce these errors using the median value of transfer delay and time correction value with many times of time stamp information exchange.

• The Transactions of the Korea Information Processing Society
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• v.13 no.4
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• pp.166-173
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• 2024

This study explores lip-sync detection, focusing on the synchronization between lip movements and voices in videos. Typically, lip-sync detection techniques involve cropping the facial area of a given video, utilizing the lower half of the cropped box as input for the visual encoder to extract visual features. To enhance the emphasis on the articulatory region of lips for more accurate lip-sync detection, we propose utilizing a pre-trained visual attention-based encoder. The Visual Transformer Pooling (VTP) module is employed as the visual encoder, originally designed for the lip-reading task, predicting the script based solely on visual information without audio. Our experimental results demonstrate that, despite having fewer learning parameters, our proposed method outperforms the latest model, VocaList, on the LRS2 dataset, achieving a lip-sync detection accuracy of 94.5% based on five context frames. Moreover, our approach exhibits an approximately 8% superiority over VocaList in lip-sync detection accuracy, even on an untrained dataset, Acappella.

• Current Industrial and Technological Trends in Aerospace
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• v.6 no.1
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• pp.116-123
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• 2008

In the launch mission, mission control systems and tracking systems need time synchronization for data monitoring and data analysis. There are several standards for time synchronization and an adequate standard is selected according to the requirement of time accuracy and cost among time synchronization standards. Oscillators are used to maintain time accuracy. There are some kinds of oscillators with diverse characteristics and an adequate oscillator can be adopted according to time accuracy. In this paper, we will specify characteristics of several oscillators and standards generally used for time synchronization. And we will also introduce TSDN(time synchronization and display network) for time synchronization in Naro Space Center.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.9
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• pp.385-392
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• 2015

In IoT(Internet of Things), it is important for wireless networks to communicate data created among resource-constrained wireless nodes, where time synchronization is needed for meaningful data creation and transmission. Time Synchronization by flooding is one of the mostly used protocols for WSN(Wireless Sensor Networks). Even though this type of scheme has some advantages over other types (i.e. a simple algorithm and independency of topology and so on), too many data transmission is required, leading to large power consumption. So, reducing transmission data is an important issue for energy efficiency in this kind of networks. In this paper, a new Flooding-based time synchronization protocol is proposed to use energy efficiently by reducing a transmitted traffic. The proposed scheme's performance has been evaluated and compared with an representative scheme, FTSP(Flooding Time Synchronization Protocol) by simulation. The results are shown that the proposed scheme is better than FTSP.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.39-47
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• 2015

In this paper, we propose a new time synchronization algorithm using CoAP(constrained-application protocol) in sensor network environment, which handles a technique that synchronizes an explicit timestamp between sensor nodes not including an additional module for time-setting and sensor node gateway linked to internet time server. CoAP is a standard protocol for sensor data communication among sensor nodes and sensor node gateway to be built much less memory and power supply in constrained network surroundings including serious network jitter, packet losses, etc. We have supplied an exact time synchronization implementation among small and cheap IP-based sensor nodes or non-IP based sensor nodes and sensor node gateway in sensor network using CoAP message header's option extension. On behalf of conventional network time synchronization method, as our approach uses an exclusive protocol 'CoAP' in sensor network, it is not to become an additional burden for synchronization service to sensor nodes or sensor node gateway. This method has an average error about 2ms comparing to NTP service and offers a low-cost and robust network time synchronization algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2022-2028
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• 2015

SpaceWire is a standard for high-speed links and networks between spacecraft components, which was invented for better, cheaper and faster on-board data handling in spacecraft. The standard defines timecode and its distribution which can be used for time synchronization among the nodes in a SpaceWire network. A timecode output from the time master which provides standard time over a SpaceWire network travels through links and routers to reach every nodes. While traveling, a timecode suffers from transmission delay and jitter which cause some difference in time synchronization among nodes. In this work, a simulator was developed using OMNeT++ to simulate the operation of a SpaceWire network and some analyses were performed on the transmission delay and jitter accompanied with a transmission of a timecode. The result will be used in the near future for the research of a precise time synchronization technique over a SpaceWire network.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.199-202
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• 2000

본 논문에서는 시각화 시스템의 설계와 평가를 통해 시각화 시스템이 어떻게 알고리즘 학습을 도울 수 있는가에 대해 기술한다. 본 논문에서 제시하는 트리 시각화 시스템은 자바로 구현하였으며 아래와 같은 특징을 제공한다. 1) 동기적, 비동기적인 상호작용 제공 2) 강의실, 연습실, 평가실의 구분 학습과 그래픽 요소 및 애니메이션의 제공 3) 사용자의 입력에 대한 즉각적인 인터랙션의 제공 4) 자바가 가능한 일반적인 웹 브라우져 상에서의 구동 등을 특징으로 한다. 본 논문에서는 여러 알고리즘 가운데 AVL 트리와 Red-Black 트리에 대한 시각화 시스템을 설계한다. 개발된 시각화 시스템은 알고리즘 학습에 활용하였으며, 평가를 통해 웹 기반 시각화 시스템을 이용한 수업이 전통적 수업에 비해 효과적이라는 결과를 도출하였다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2009.04a
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• pp.325-326
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• 2009

다각촬영카메라를 제어하고 GPS/INS와 동기화하기 위해서 다각촬영 카메라 제어 장비(MLCC)를 개발하였다. 이는 5대의 카메라에 촬영신호를 보내고 촬영시각을 GPS/INS와 동기화 하여 정확한 촬영시각을 기록하기 위한 장비이다. 개발 결과를 검증하기 위하여 Applanix사의 POS 시스템과 Leica-Geosystem의 IPAS20을 병렬로 연결하여 그 결과를 비교하였다. 비교 결과 다각촬영 카메라를 제어하기에 충분한 정밀도를 보여 주었으며, 차기년도 경량화를 진행하고자 한다.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.6
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• pp.127-134
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• 2016

WBSN (Wireless Body Sensor Network), also called WBAN (Wireless Body Area Networks) generally, is a kind of WSN (Wireless Sensor Network) applications, which is composed of the various sensor nodes residing in human body embodied or in wearable way. The measured data at each sensor node in WBSN requires being synchronized at sink node for exact analysis for status of human body, which is like WSN. Although many time synchronization protocols for WSN has been already developed, they are not appropriate to WBSN. In this paper, a new time synchronization protocol for WBSN considering the characteristics of WBSN is proposed. The proposed scheme is not only simple, but also consumes less power, leading to increasing network life time. We will show that the proposed scheme is appropriate to WBSN by evaluating its performance by simulation.