• International Journal of Internet, Broadcasting and Communication
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• v.5 no.2
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• pp.1-4
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• 2013

With the recent development of the ubiquitous computing technology, there are increasing interest and research in technologies such as sensors and RFID related to information recognition and location positioning in various ubiquitous fields. Especially, RTLS (Real-Time Locating Services) dealing with spatio-temporal data is emerging as a promising technology. For these reasons, the ISO/IEC published RTLS standard specification for compatibility and interoperability in RTLS. Therefore, in this paper, we designed and implemented Spatio-temporal Query Processing Systems for efficiently managing and searching the incoming Spatio-temporal data stream of moving objects. Spatio-temporal Query Processing Systems's spatio-temporal middleware maintains interoperability among heterogeneous devices and guarantees data integrity in query processing through real time processing of unceasing spatio-temporal data streams and two way synchronization of spatio-temporal DBMSs. Web Server uses the SOAP(Simple Object Access Protocol) message between client and server for interoperability and translates client's SOAP message into CQL(Continuous Query Language) of the spatio-temporal middleware.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.11
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• pp.2991-3000
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• 1996

In this paper, an effective neural acquisition system is suggested for acquisition of the DS/SS communication system. The suggested system uses a binary neural network which geometrically analyzes and learns a given PN sequence in the binary field. the probabilities of detection and false alarm are obtained and are compared to simulation values. The equation of the mean acquisition time is derived and is compared to the doubledwell time of the serial serial search system. The significant improvement of the performance is demonstrated. As the length of synchronization sequence becomes longer and the number is increased, the performance is improved.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.89-90
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• 2008

We present an implementation and it's real-sea test of an underwater acoustic communication system, which allows the system to reduce complexity and increase robustness in time variant underwater environments. For easy adaptation to complicated and time-varying environments of the ocean, all-digital transmitter and receiver systems were implemented. For frame synchronization the CAZAC sequence was used, and QPSK modulation/demodulation method with carrier frequency of 25kHz and a bandwidth of 5kHz were applied to generate 10kbps transmission rate including overhead. To improve transmission quality, we used several techniques and algorithms such as adaptive beamforming, adaptive equalizer, and convolution coding/Viterbi decoding. For the verification of the system performance, measurement of BER has been done in a very shallow water with depth of 20m at JangMok, Geoje. During the experiment, image data were successfully transmitted up to about 9.6km.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.1
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• pp.9-15
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• 2012

Recently, as the development of 3D contents service, production of 4D media that user can feel physical effects by the scene of movie has been increased. This 4D media uses the SMMD (Single Media Multiple Devices) method to give users enhanced effects with multiple devices playing rather than the SMSD (Single Media Single Device) method with single device playing in a smart TV environment. To give more sensible effects to users, from the beginning of making one media, we produced 4D media that consists of 3D contents and the SEM (Sensory Effect Metadata) to define effects of the scene. 4D media is transmitted to a HS (Home Server) to represent 3D contents in 3DTV and multiple devices with synchronized way. In this paper, we suggested the concept and overall 4D media broadcasting service system architecture, aggregator time acquisition, media time scheduling, real-sense device scheduling, evaluation results, user interfaces and implemented devices.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.690-696
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• 2010

Web-based virtual collaboration is increasingly gaining popularity in almost every area in our society due to the fact that it can bridge the gap imposed by time and geographical constraints. However, in medical field, such collaboration has been less popular than other fields. Some of the reasons were timeliness, security, and preciseness of the information they are dealing with. In this paper, we are proposing a web-based distributed medical collaboration system called Virtual Collaboration System for Medicine (VCSM) for medical doctors that meet the needs. The proposed system consists of two parts - multimedia presentation and recordable virtual collaboration. The former supports synchronized multimedia presentation using Synchronous Multimedia Integration Language (SMIL.) It allows synchronization of the contents of a PowerPoint presentation file and a video file. The presentation may be provided to the participants before the discussion begins. Next, in the virtual collaboration stage, participants can use text along with associated symbols during the discussion over the presented medical images. The symbols such as arrows or polygons can be set or removed dynamically to represent areas of interest in digital images using so called layered architecture that separates image layer from annotation layer. XML files are used to record participants' opinions along with the symbols over some particular images

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.163-177
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• 1999

Polishing work for a curved surface die demands simple and repetitive operations and requires much time while it demands also high precision. Therefore it is operated by a skilled worker in handiwork. However the workers avoid gradually a polishing work because of the poor environmental conditions such as dust and noise. In order to reduce the polishing time and to alleviate the problem of shortage of skilled workers, an automatic polishing robot system which is composed of a polishing robot with two degrees of freedom motion and pneumatic system is developed, and it is attached to machining center with three degrees of freedom. The system keeps the polishing tool vertically on the surface of die and maintains constant pneumatic pressure. The polishing robot with DSP(digital signal processor) controller is controlled by sliding mode control. A synchronization between machining center and polishing robot is accomplished by using M code of machining center. A performance experiment for polishing work is executed by the developed automatic polishing robot system. The result shows that the developed automatic polishing robot has a good performance and well polished workpiece surface is obtained.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.44-50
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• 2002

The fast Fourier transform (FFT) is a good method to estimate spectral density, but the frequency resolution is limited to the sampling window, and thus the precise characteristics of the spectral density for short signals are not clear. To solve the limitation, a multiple band-pass filter was introduced to estimate the precise time course of the spectral density for flash visual evoked potentials (VEPs). Signals were recorded during -200 and 600 ms using balanced noncephalic electrodes, and sampled at 1 K Hz in 12 bits. With 1 Hz and 10 ms resolutions, spectral density was estimated between 10 and 100 Hz. Background powers at the alpha-and beta-bands were high over the posterior scalp, and powers around 200ms were evoked at the same bands over the same region, corresponding to P110 and N165 of VEPs. normalized's spectral density showed evoked powers around 200 ms and suppressed powers following the evoked powers over the posterior scalp. The evoked powers above the 20Hz band were not statistically significant. However, the gamma band was significantly evoked intra-individually; details in the gamma bands were varied among the subjects. Details of spectral density were complicated even for a simple task such as watching flashes; both synchronization and desynchronization occurred with different distributions and different time courses.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.44-49
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• 2006

최근 무선 통신의 발달과 임베디드 시스템의 확산으로 주변 상황을 감지하고 통신할 수 있는 저전력 장치인 무선 센서 네트워크에 대한 연구가 많이 진행되고 있다. 무선 센서 네트워크를 구성하는 노드들 간의 동기화, 순서화, 그리고 일관성 유지를 위하여 시간 동기화는 반드시 필요하다. 하지만 지난 20여 년간 연구되어진 분산 시스템에서의 시간 동기화 방법들은 풍부하지 않은 자원과 에너지 소모 등을 고려해야 하는 무선 센서 네트워크의 특성상 그대로 적용하기에는 어려운 점이 많다. 이에 본 논문에서는 무선 센서 네트워크에서의 누적 시간 정보를 이용한 시간 동기화 방법을 제안한다. 무선 브로드캐스트의 특성을 활용하여 시간 동기화의 제약 조건을 완화하여 높은 정확성을 제공하면서 한 번의 브로드캐스트 메시지만으로 시간을 동기화함으로써 에너지 손실을 최소화하였다. 이를 위해 송신자-수신자 방식의 구조에서 송신자는 시간 동기화를 위한 시간 정보를 브로드캐스트하고, 수신자는 누적된 시간 정보를 통해 편차와 편차율을 계산하여 송신자의 시간을 추정하고 동기화된 시간인 가상 시간을 계산하였다. 전체 센서노드들의 시간이 동기화할 수 있음을 분석하고 실험을 통해 효율성을 확인하였다.

• Journal of Internet Computing and Services
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• v.7 no.6
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• pp.143-155
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• 2006

In this paper, we suggest a network game system that can support video game based on multi-platform for multi-user video game, Latency occurring from the load fluctuation in realtime network game is overcomed by using an initial delay buffering scheme on client, when a real-fire game is played, and shows that stable play for a game is achieved as the result of the scheme. Also, We suggest a retransmission algorithm based on the history of game commands, and this Algorithm supplement shortcomings for packet loss and pocket error on UDP communication.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.6-12
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• 2008

In uplink cable modem link operated in time-division multiple access mode, it is crucial to employ a suitable preamble pattern enabling frame detection, coarse timing/carrier recovery. Preamble pattern based on the constant envelope zero autocorrelation sequence is proposed for the uplink cable modem compliant to the data over cable service interface specification. Frame detection, coarse/fine timing and carrier recovery algorithms suitable for the proposed preamble pattern are also proposed. We check up the performances using numerical results.