• Journal of Advanced Navigation Technology
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• v.7 no.2
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• pp.141-148
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• 2003

This paper presents and compares several techniques that detect the symbol rate of unknown received signal. Symbol rate is detected from the power spectral density of the circuits such as the delay and multiplier circuit, the square law circuit, and analytic signal, etc. As a result of discrete Fourier transform of the output signals of these circuits, a lot of spectral lines and some peaks appear in frequency domain and the position of first peak is corresponding to the symbol rate. If a spectral line on the frequency that is not located in symbol rate is larger than the first peak, the symbol rate is erroneously detected. Thus, the ratio between the value of first peak and the highest side spectral line is used for the measure of the performance of symbol rate detector. For the MPSK modulation, the analytic signal method shows better performance than the delay and multiplier and square law circuits when the received signal power is lager than -20dB. It is also noted that the delay and multiplier circuit is not able to detect the symbol rate for the QAM modulation.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.113-118
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• 2017

As interest in mobile devices and networks has increased recently, voice over internet protocol (VoIP) service, which is a technology for transmitting voice data using an existing internet protocol (IP) network, has rapidly spread, Cheap voice call service has become possible. As the digital broadcasting service becomes popular, hybrid fiber coaxial (HFC) network technology, which uses broadband cable network through fusion of broadcasting and communication, utilizes existing communication system and network equipment to provide various new services such as interactive broadcasting service. Therefore, if UGS-AD is applied to VoCM and RTPS is applied to MTA in order to guarantee the quality of voice data in actual HFC Internet service network, it is possible to smoothly perform voice data transmission in narrow upstream band which is a problem in actual commercial HFC network We also proposed a method to improve VoIP service by improving QoS of voice data in HFC Internet service network.

• Journal of KIISE:Software and Applications
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• v.26 no.9
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• pp.1052-1060
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• 1999

이제까지 비디오 데이타베이스를 모델링하기 위한 많은 연구들이 수행되었지만 그 모든 모델들에서 다루는 비디오 데이타는 사용자의 개입이 없을 때 항상 미리 정의된 순서로 보여진다는 점에서 정적 데이타 모델로 간주될 수 있다. 주문형 뉴스 서비스, 주문형 비디오 서비스, 디지털 도서관, 인터넷 쇼핑 등과 같이 최신 비디오 정보 서비스를 제공하는 비디오 데이타베이스 응용들에서는 빈번한 비디오 편집이 요구되는데 실시간 처리가 바람직하다. 이를 위해서 기존의 비디오 데이타 내용이 변경되거나 새로운 비디오 데이타가 생성되어야 하지만 이제까지의 비디오 데이타 모델에서는 이러한 비디오 편집 작업이 일일이 수작업으로 수행되어야만 했다. 본 논문에서는 비디오 편집에 드는 노력을 줄이기 위해서 객체지향 데이타 모델에 기반하여 DVID(Dynamic Video Object Data Model)라는 동적 비디오 객체 데이타 모델을 제안한다. DVID는 기존의 정적 비디오 객체뿐만 아니라 사용자의 개입없이도 비디오의 내용을 비디오 데이타베이스로부터 동적으로 결정하여 보여주는 동적 비디오 객체도 함께 제공한다.Abstract A lot of research has been done on modeling video databases, but all of them can be considered as the static video data model from the viewpoint that all video data on those models are always presented according to the predefined sequences if there is no user interaction. For some video database applications which provides with up-to-date video information services such as news-on-demand, video-on-demand, digital library, internet shopping, etc., video editing is requested frequently, preferably in real time. To do this, the contents of the existing video data should be changed or new video data should be created, but on the traditional video data models such video editing works should be done manually. In order to save trouble in video editing work, this paper proposes the dynamic video object data model named DVID based on object oriented data model. DVID allows not only the static video object but also the dynamic video object whose contents are dynamically determined from video databases in real time even without user interaction.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.17-22
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• 2009

DaVinci processors are popular media processors for implementing embedded multimedia applications. They support dual core architecture: ARM9 core for video I/O handling as well as system management and peripheral handling, and DSP C64+ core for effective digital signal processing. In this paper, we propose our efforts for optimal implementation of object tracking algorithm in DaVinci-based smart camera which is being designed and implemented by our laboratory. The smart camera in this paper is supposed to support object detection, object tracking, object classification and detection of intrusion into surveillance regions and sending the detection event to remote clients using IP protocol. Object tracking algorithm is computationally expensive since it needs to process several procedures such as foreground mask extraction, foreground mask correction, connected component labeling, blob region calculation, object prediction, and etc. which require large amount of computation times. Thus, if it is not implemented optimally in Davinci-based processors, one cannot expect real-time performance of the smart camera.

• Journal of Internet of Things and Convergence
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• v.5 no.2
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• pp.21-26
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• 2019

Wisdom contents is made by an ordinary person and contains life tips helpful in general. As the existing copyright management systems are designed for the corporate or professional authors, it's not easy to use and requires high cost for the ordinary person to get the copyright. Blockchain based system can notarize the block of transactions without help of trustful third party such as existing copyright protection center. Thus, blockchain based copyright protection model is needed to protect the ordinary author's copyright. In this study, we propose the smart contract based copyright protection model which run on the blockchain network. The proposed model consists of smart contract creation, contents purchase and profit sharing stages. The digital signature scheme is used to get the contract agreed by the seller and the author. The smart contract stores the author information, contents information and the percentage of the share as states. If the contents is sold, the sales tokens are redistributed to the author and the seller according to the share. The proposed model can be applied to the ordinary person's copyright registration and management for Wisdom contents distributed in cafe, blog, YouTube, etc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.12
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• pp.2232-2240
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• 2017

IMO has made AIS and VHF mandatory for international sailing vessels through SOLAS, and korea if mandating specific vessels through the law for safety of vessels and the ship installation technology standards. However, due to various communication equipments and complicated usage method, malfunction occurs, and the response delay to the actual structure signal often causes human accidents. So recently, as a part of GMDSS modernization, maritime communication devices are attempting to interwork and integrate different types of marine communication system in order to construct a next generation maritime communication system. In this paper, we describe a technique to implement the DSC function by interlocking and integrating the AIS device and VHF. We will present the basis for achieving domestic technical standards and standardization through the linking algorithm of the data that can extract the ship information from AIS and utilize it the DSC function of VHF.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.8
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• pp.1069-1082
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• 1993

The International Organization for Standardization(ISO) has undertaken an effort to develop a standard for video and associated audio on digital storage media. This effort is known by the name of the expert group that started if : MPEG-Moving Picture Experts Group Is currently part of the ISO-I EC/J TC1/SC2/WG11. The promise of MPEG-2 is that a video signal and its associated audio can be compressed to a bit rate of about 10 Mbits/s with an acceptable quality. In this paper, the implementation of a video compression simulator based on MPEG-2 Video Test Model 2(TM2) is described and analyzed according to the simulation results. The implemented simulator is also applied to code HDTV sequences at the several bit rates. Some computer simulation results using the MPEG and the HDTV test sequences are given. In addition, some techniques which can improve the coding efficiency of the implemented video compression simulator are also suggested.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.6
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• pp.1064-1074
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• 1994

In this paper, an optimum TCM(trellis coded modulation)combined with CPM(continuous phase modulation) signal is investigated, and the performances are evaluated on the two-ray fading channel, which is one of the well-known frequency-selected because of their relatively good power and spectrum efficiency, and the modulation index is varied from 0.1 to 0.6. The performance is evaluated for each modulation index. The constraint length of the encoder, which is comprised in TCM, is chosen to be 2 and 3. From the performance evaluations, when the constraint length is 3 and modulation index 0.5, a power gain if the optimum TCM over the scheme without coding is observed to be 2.0dB for 1REC and 2.1dB for 3RC, respectively, on the fading channel. Thus, a significant improvement on the line quality is expected when the optimum TCM presented in this paper is employed in digital mobile radio applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.12
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• pp.1327-1337
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• 2014

In cellular communication systems employing millimeter wave (mmWave) bands for a link, a large amount of training time and network resources will be required to find a serving BS with the best transmit and receive (Tx-Rx) beam pair if downlink control signals are used. In this paper, a tracking technique for OFDM-based cellular communication systems with a mmWave link, where an analog beamforer is used at the mobile station (MS) and a digital beamformer is used at the BS, is proposed using an uplink signal. A technique to select a serving BS with the best beam pair is described using the uplink preamble sequence based on Zadoff-Chu sequence and a metrics which can be used to identify parameters such as beam ID (BID), MS ID (MID), and direction-of-arrival (DoA). The effectiveness of the proposed technique is verified via simulation with the spatial channel model (SCM) for a moving MS in mmWave cellular systems.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2195-2196
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• 2006

This study is for implementation of PC based Motor fault diagnosis system. By using harmonics and current signals of the motor, this system diagnoses the motor condition by accumulated harmonic contribution rate. In this proposed system that was composed of 5 parts. A sensor, connection box, evaluation board, device server, and main computer are those. There were two types of sensor, one was harmonic sensor the other was current sensors. The signal was acquired by sensor, and transferred to evaluation board. Second one is connection box. Because the output type of sensor and input type of evaluation board is different, connection box was necessary. Third one was evaluation board. The signal from the sensor was converted to digital signal in evaluation board. And this signal was transferred to device server. Fourth one was device server. Device server transferred the data from evaluation board to main computer. And the last one was other parts controlled by main computer. In main computer, there were communication and diagnosis algorithms. The result was derived by main computer. In the result, there were 12 categories and 5 levels of motor conditions. The proposed system had some advantages comparing with stand alone type commercial motor fault diagnosis system. The first, by using remote access it was easier to get the conditions of motor. The second, there was no need to handle the sensors when users measured the motor signals. By this property, no one was necessary at motor location site. The third, this system was less restricted by times and places than commercial stand alone type diagnosis system. Therefore users can operate this system only using the main computer. Once the sensors are installed at the motor, users doesn't need to move to check up the condition of motors. Moreover, if there is ethernet hub, many motors can be not only diagnosed at once but also decreased its cost.