• Journal of Advanced Navigation Technology
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• 제8권2호
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• pp.129-135
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• 2004

In this paper, the practical applications of the pseudolite are explained with the basic concept of the pseudolite. Many researches have been developed to improve the performance of the GPS. Most of those researches need the extra equipments. But without the extra equipments, the performance of GPS can be improved only with the change in the software in GPS system. In this paper, the pseudolite and the integrated navigation system including GPS as well as pseudolite only with navigation system for the demand of more precise navigation system are introduced. Also, the advantage of the pseudolite is confirmed by some simulations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 한국방송∙미디어공학회 2020년도 추계학술대회
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• pp.260-262
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• 2020

본 논문은 6DOF 위치기반 자기장 센서(Liverty Latus, Pollhemus)를 사용한 가상현실 방송제작에서 사용할 수 있는 인터랙티브 증강현실 시스템, K-Pointer를 제안한다. 우리는 방송에서 추적 및 인식의 정확성을 높이기 위해 Pollemus사의 6DOF 자기장기반 위치 추적 센서 리버티(수신부,소스)와 라투스(송신부,마커), 그리고 4입력 버튼장치를 결합한 인터페이스를 가지고 기존 방송용 증강현실 시스템과 통합하여 새로운 인터랙티브 증강현실 시스템을 개발하였다. 본 시스템은 방송용 증강현실 그래픽 합성 시스템(수신부)과 센서의 위치정보와 버튼 이벤트를 전송하는 시스템(송신부)으로 구성되며, 센서추적정보와 버튼이벤트 정보는 UDP로 실시간으로 수신부로 전송된다. 우리는 사용자 손의 모션과 버튼이벤트로 그래픽 정보를 인터랙티브하게 제어할 수 있게 하였다. 결과적으로 본 시스템은 기존의 합성중심의 방송용 증강현실 시스템을 사용자의 모션 기반 그래픽을 제어할 수 있는 인터랙티브 증강현실시스템으로 그 기능을 확장 시킬 수 있게 한다. 제안된 시스템은 광학식 추적을 하지 않기 때문에 조명의 변화에 영향이 없으며, 라투스 수신기가 작기 때문에 손에 쥐었을 때 거의 보이지 않고 가려도 추적이 강인하여 버튼장치를 통해 사용자가 정확한 이벤트로 직접 그래픽을 그리거나 쉽게 제어할 수 있는 장점이 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제29권1D호
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• pp.135-143
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• 2009

Integrating the Global Positioning System (GPS) and Inertial Navigation System (INS) sensor technologies using the precise GPS Carrier phase measurements is a methodology that has been widely applied in those application fields requiring accurate and reliable positioning and attitude determination; ranging from 'kinematic geodesy', to mobile mapping and imaging, to precise navigation. However, such integrated system may not fulfil the demanding performance requirements when the baseline length between reference and mobil user GPS receiver is grater than a few tens of kilometers. This is because their positioning/attitude determination is still very dependent on the errors of the GPS observations, so-called "baseline dependent errors". This limitation can be remedied by the integration of GPS and INS sensors, using multiple reference stations. Hence, in order to derive the GPS distance dependent errors, this research proposes measurement processing algorithms for multiple reference stations, such as a reference station ambiguity resolution procedure using linear combination techniques, a error estimation based on Kalman filter and a error interpolation. In addition, all the algorithms are evaluated by processing real observations and results are summarized in this paper.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제16권11호
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• pp.1138-1146
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• 2005

This paper makes a study of a formulation of net filter discrimination(NFD) and its computation for analyzing adjacent channel interference and suggests a systematic algorithm for calculating protection ratios of co-channel and adjacent channel applicable to frequency coordination in the fixed radio relay networks. It is shown that adjacent channel protection ratio can be derived from two factors: One is NFD depending upon receiver filter characteristic as well as transmitter spectrum mask and the other is co-channel protection ratio given by a function of fade margin, modulation scheme, and allowable interference. Actually to show the computing procedure from transmitter spectrum mask and receiver filter characteristic, NFD has been obtained for channel bandwidth of 29.65 and 40 MHz at 6.2 and 6.7 GHz band, respectively. According to the results, NFDs at the first adjacent channel of 29.65 and 40 MHz provide 27.4 and 28.9 dB, respectively. From these data, adjacent channel protection ratios corresponding to each channel bandwidth yield 47.5 and 46.3 dB for a given 64-QAM and 60 km. The proposed method gives some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter radio relay networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제28권10C호
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• pp.995-1006
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• 2003

It is well know that in the wireless communication systems the transmitted signals can suffer from multipath fading due to the wave propagation characteristics and the obstacles over the paths, resulting in serious reduction in the power of the received signals. However, it is possible to take advantage of the inherent diversity imposed in the multipath reception if the underlying channel can be properly estimated. One of the diversity reception methods in this case is Rake processing. In this paper we study the Rake receivers for the direct-sequence spread-spectrum communication systems utilizing PN (pseudo noise) sequences to achieve spread spectrum. A conventional Rake receiver can use the finite-duration impulse (FIR) filter followed by the PN sequence demodulator, where the FIR filter coefficients are the reverse-ordered complex conjugate values of the fading channel impulse response estimates. Here, we propose a new Rake processing method by replacing the aforementioned PN code sequence with a new set of optimum demodulator coefficients. More specifically, the concept of the new optimum Rake processing is first introduced and then the optimum demodulator coefficients are theoretically derived. The performance obtained using the new optimum Rake processing is also calculated. The analytical results are verified by computer simulation. As a result, it is shown that the new optimum Rake processing method improves the MSE performance more than 10 dB over the conventional one using the fixed PN sequence demodulator. It is also shown that the new optimum Rake processing method improves the MSE performance about 10 dB over the Adaptive Correlator that performs the combining of the multipath components and PN demodulation concurrently. And finally, the MSE performance of the optimum Rake demodulator is very close to the MSE performance of OPSK demodulator under the AWGN channel.

• Journal of KIISE:Software and Applications
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• 제30권10호
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• pp.925-937
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• 2003

The input of digital TV software is the Transport Stream, which utilizes the moving picture compression technique, MPEC-2 (Moving Picture Experts Groups-2). MPEG-2 TS consists of the complicated table hierarchy and internal relationships, as well as the various restrictions with regards to system standard of digital TV software in determining the field values of transport stream. However, the general MPEG-2 TS generation tool produces transport streams solely based on the MPEG-2 TS specification itself, and does not consider the interaction between modulo features or modules themselves, which construct digital TV software. In this paper, we propose a method to systematically generate MPEG-2 TS test data, namely‘Test Stream’, for digital TV software. We present the experiment result where the test stream derived from our developed tool according to the proposed method was applied to the actual digital TV software settop-box, and then analyze the result. Apart from other existing MPEG-2 TS generation tools, the advantage of our method is that not only is it capable of generating various levels of test streams including digital TV software module, integration, and system testing, but also detecting errors and analyzing their causes.

• Journal of the Korean Geographical Society
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• 제47권4호
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• pp.592-605
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• 2012

This article reviewed issues in Korean geographical journals: web GIS and National GIS. Web GIS in Korea is now evolving to mobile GIS, which requires portable hardware, wireless Internet, and GPS receiver. The new trend of mobile GIS is using a smart phone. Recently, a variety of studies for the mobile App and mobile Web in Korea has been developed. With explosive information on the Web 2.0, the Korean government has built the Human-Oriented Geographic Information System (HOGIS) in which Ontology was implemented for semantic query on the Web. On the government side, Korean government has produced various nationwide data through 4-phase NGIS project. Current NGIS ($4^{th}$ phase: 2011-2015) moves toward a Korean Green Geospatial Society using geospatial information as a new growth engine for the future.

• Archives of design research
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• 제11권2호
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• pp.59-68
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• 1998

A work as human's creatures are transformed to bits and multimedia. In the modem society which is governed by simulation, infornlation is symbolized and becoming easily reached to anyone. Thus, collections of image and composition can show a new world beyond the ethical viewpoint. The problem with worries about the differnce between the original and a copy and disappearence of the meaning in postmodern era is the problem of how to set the intellectual properties and copyrights.In this situation, sharing of information according to the theoretical concepts and process of digitalization of photos in the era of information-intensive society was presented. The ethics of intellectual properties and copyrights and in postmordern era were driven. After reviewing the intellectual properties in the era of national information infrastructure of twenty-first century and by identifying the problems, the directions of what we have to do as image makers, and the intellectual properties and copyright.

• Journal of Broadcast Engineering
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• 제9권1호
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• pp.74-82
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• 2004

In digital broadcasting, applications are computer programs executed by the set-top box(TV receiver) , and synchronized applications are those that perform tasks at the specified moments in the underlying video. This paper describes important concepts, standards, and skills needed to implement synchronized applications and explains how to integrate them to implement these applications. This Paper assumes the European data broadcasting standard, DVB-MHP. In DVB-MHP, scheduled stream events are recommended as a means of synchronizing applications with video streams. In this method, the application receives each stream event, and executes the action associated with the stream event at the time specified in the stream event. Commercially available stream generators, i.e., multiplexers, do not generate transport streams that support scheduled stream events. So we used a stream generator implemented in our lab. We implemented a synchronized application where the actions triggered by stream events are to display graphic images. We found that our synchronized application processes scheduled stream events successfully. In our experimentation, the stream events were synchronized with the video and the deviation from the intended time was within 240 ㎳, which is a tolerance for synchronization skew between graphic images and video.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제41권6호
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• pp.481-487
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• 2013

In GPS(Global Positioning System)/INS(Inertial Navigation System) integrated navigation systems, GPS antennas and an inertial measurement units are usually installed outside and inside of the vehicle, respectively. By the difference of installed locations, performance of GPS/INS integrated navigation systems is affected by lever arm errors. For more accurate navigation, lever arm errors need to be compensated correctly since it directly affects the accuracy of navigation states. This paper proposes an effective lever arm error compensation method that utilizes velocity measurements of GPS and INS. By an experiment, feasibility of the proposed algorithm is verified. It is also shown that lever arm compensation is especially important when vehicles are experiencing rotational movements.