• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.104.1-104.1
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• 2014

한국우주전파관측망(KVN, Korea VLBI Network)의 우주전파수신시스템(22GHz, 43GHz, 86GHz, 129GHz의 4파수 동시관측 시스템)으로부터 수신된 전파신호를 디지털 신호로 바꾸어 주는 장치인 초고속 샘플러의 국산화와 성능 향상을 위하여, 우리는 1GHz 샘플링을 할 수 있는 전파관측 자료의 샘플링 장치를 설계, 제작하였다. GHz 샘플링 기본 기술 확보와 독자 개발을 위하여 제작된 1GHz 샘플러를 KVN울산전파천문대에 설치하여 관측 시험한 결과, 연구 관측에 적용할 수 있음을 보여 주었다. 한편, 광대역 관측과 e-VLBI 구현을 위하여 샘플러에서 직접 첨단망으로 VDIF(VLBI Data Interchange Format, VLBI 자료전송 규격)의 자료를 보낼 수 있는 차세대 4GHz 샘플러를 개발 중에 있다. 이번 발표에서는 1GHz 샘플러에 대한 개발 내용과 관측 결과 및 향후 계획을 소개한다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1741-1742
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• 2008

위성을 이용한 통신 및 방송은 양방향 서비스 시대를 맞이하고 있으며, 위성 인프라는 통신망 back-up 개념을 벗어나 이동 휴대 그리고 지상 인프라 구축 및 운영이 어려운 지역 및 시설을 중심으로 광역 통신 및 방송의 근간 망 구성으로 나아가고 있다. 또한, 위성 통신 및 방송은 재난 방재 및 긴급 복구, 산업 시설 감시 및 측정데이터 모니터링 등 지상 인프라와 상호 보완적인 2 중망 또는 기간 망으로 활용되고 있다. 한국수자원공사에도 수문관측망 및 감시제어를 포함한 원격 데이터 취득 및 정보제공 등 많은 부분에 위성통신망이 적용되고 있으며, 수문관측망에 사용중인 위성통신망의 주파수 임대기간과 위성통신장비의 내용년수 도래에 따른 시스템 개선 및 대체방안 모색이 필요한 실정으로이다. 또한 수위, 우량과 같은 기존의 저속 위성망에 비하여 기술발전 및 데이터의 다양화에 따른 화상, 동영상과 같은 멀티미디어 데이터 등 초고속, 광대역 위성통신망을 구축할 수 있는 방안에 대하여 살펴보고자 한다.

• Korean Journal of Remote Sensing
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• v.7 no.2
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• pp.113-130
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• 1991

Meterological satellites have taken their important place as astandard observing platform from which to measure weather. Specially, they provide a useful information about the weather of wide dessert or sea. This information is really helpful to understand the field of satellite meteorology. Several leading countries, for example, USA, EC, Russia, and Japan, launch two different satellites, both Geostationary and Polar orbiting satellite system. Hewever no technology is developed to our own groundstation for NOAA satellite. The purpose of this paper is to build a home-made NOAA APT groundstation and image processing system to supply this system to secondary school or college.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.105.2-105.2
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• 2014

Mark6는 최대 16Gbps의 데이터 입출력을 지원하는 차세대 기록 시스템으로서 올 하반기 내에 KVN의 관측 연구에 활용되기 위해 현재 기록 실험이 진행 중에 있다. VDIF(VLBI Data Interchage Format) 기반의 Mark6가 KVN 각 사이트에서 실제 관측에 활용되기 위해서는 FILA10G, VOA(VSI Optical Adapter) 등의 VSI-VDIF 컨버터가 수반되어야 하며 샘플러, DAS(Data Acquisition System) 등 내부적으로도 많은 시스템 변화가 필요하다. 본 발표에서는 기본 사양, 동작 원리 등 Mark6에 대한 간단한 소개를 시작으로 데이터 기록 실험 결과에 대해 설명하고자 한다. 나아가 이를 기반으로 향후 KVN의 광대역 관측 수행을 위한 Mark6의 활용 방안에 대해 살펴보고자 한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.6
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• pp.1097-1108
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• 2019

In VLBI(Very Long Baseline Interferometry), the observed data created in many observatories which are far away from each other should be collected in correlation center for data analysis. Traditionally, observed data is moved by transportation such as car or airplane. But it is replaced with data transfer over the network rapidly as the advancement of information technology, and therefore, international cooperative research is also now more widely expanding. e-KVN(electronic Korean VLBI Network) has been upgraded two times so the network interface of KVN has been evolved to the highest specification of 100GbE. During this time period, the portion of network usage for VLBI observations and experiments in KVN has been increased exponentially. In this paper, we describe KVN VLBI system and network technology for the performance upgrade and advanced status monitoring between three radio astronomy observatories and Daejeon correlation center with KREONET(Korea Research Environment Open NETwork). Furthermore, future plan of e-KVN for the implementation of wide band VLBI observation will be also briefly discussed.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.4
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• pp.175-181
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• 2015

In this paper, we propose a design method for a digital filter using software in order to analyze the radio astronomy observation data. Recently the analysis method for radio astronomy observing system is transferring from hardware to software by developing of state-of-the-art of computer system. The existing hardware system is not able to easily change the specification because it is implemented to meet special requirements and it takes a high cost and time. In case of software, however, it has an advantage to implement with small cost if open software is used, and flexibly changes to satisfy the desired specification. But, in order to analyze the massive data like radio astronomy with software, the good performance system is needed for computer. Therefore, this paper proposes a digital filter design method using software with the same performance as that of digital filter implemented with hardware in observation system which is operated by the KVN(Korean VLBI Network). To design a digital filter, the proposed method is performed with standard C language and the simulation is conducted with GNU(GNU's Not Unix) Octave and investigated to show its effectiveness. In addition, for the high speed operation of the designed digital filter, the SSE(Streaming SIMD Extensions) library is adopted for available parallel operation. By the proposed digital filter, the digital filtering is performed for the wide band observation data in the KVN observation mode, the filtering result of narrow band observation has no ripple inside of stop band, and confirmed the effectiveness of the proposed method.

• Journal of the Institute of Convergence Signal Processing
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• v.18 no.2
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• pp.55-61
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• 2017

In radio astronomy, high-capacity HDDs are being used to save huge amounts of HDDs in order to record the observational data. For VLBI observations, observational speeds increase and huge amounts of observational data must be stored as they expand to broadband. As the HDD is frequently used, the number of failures occurred, and then it takes a lot of time to recover it. In addition, if a failed HDD is continuously used, observational data loss occurs. And it costs a lot of money to buy a new HDD. In this study, we developed the integrity verification system of the Serial ATA HDD using FirmOS. The FirmOS is an OS that has been developed to function exclusively for specific purposes on a system having a general server board and CPU. The developed system performs the process of writing and reading specific patterns of data in a physical area of the SATA HDD based on a FirmOS. In addition, we introduced a method to investigate the integrity of HDD integrity by comparing it with the stored pattern data from the HDD controller. Using the developed system, it was easy to determine whether the disk pack used in VLBI observations has error or not, and it is very useful to improve the observation efficiency. This paper introduces the detail for the design, configuration, testing, etc. of the SATA HDD integrity verification system developed.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1175-1182
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• 2021

The receiver of each radio telescope of KVN, has a sampler that converts astronomical radio signal to digital data. The ability of this sampler (the bandwidth, sampling frequency, and sampling bits) is improved by sqrt(n), if the bandwidth is increased by n times, and the number of observable objects increases exponentially in the case of continum spectrum radio sources. As the bandwidth increases, there are the more spectrum lines that can be simultaneously monitored in the radio source. This will greatly expand the research area in astronomical radio observation. For this reason, we are trying to independently develop the technology of the fast digital sampler. Therefore, based on the research experience and technology accumulated so far, An ability of sampling up to 3.5 GHz, that can vary the sampling frequency and can observe in a wider band, was designed and made for proto-type. In this study, we introduce the development details and test results for new sampling system.

• Journal of the Korean Geophysical Society
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• v.10 no.1
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• pp.1-12
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• 2007

A method to quickly estimate broadband moment magnitudes (Mwp) to warn regional and teleseismic tsunamigenic earthquakes is tested for application of the method to the different seismic observation environment. In this study, the Mwp is calculated by integrating far-field P-wave or pP-wave of vertical component of displacement seismograms in time domain from earthquakes, having magnitude greater than 5.0 and occurred in and around the Korean peninsula from 2000 to 2006. We carefully set up the size of the time window for the computations to exclude S wave phases and other phases following after the P wave phase. The P wave velocities and the densities from the averaged Korean crustal model are used in the computations. Instrumental correction was performed to remove dependency on the seismograph. The Mwp after the instrumental correction is about 0.1 greater than the Mwp before the correction. The comparison of our results to the those of foreign agencies such as JMA and Havard CMT catalogues shows a higher degree of similarity. Thus our results provide an effective tool to estimate the earthquake size, as well as to issue the necessary information to a tsunami warning system when the effective earthquake occurs around the peninsula.

• Journal of Navigation and Port Research
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• v.32 no.10
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• pp.805-811
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• 2008

This paper presents a design of RFID(Radio Frequency Identification) tag antenna which is available for a vehicle's side mirror and directivity characteristics by mr body. The proposed Tag antenna is designed symmetrical structure to improve the broad bandwidth characteristic and the readable range. A proposed tag antenna($30\;mm{\times}24\;mm{\times}1\;mm$) has resonant frequency at 910 MHz and bandwidth is 780 MHz ($540\;MHz{\sim}1320\;MHz$). The chip impedance is the 16 - $j131\;{\Omega}$ and the complex conjugate impedance of commercial chip has been used for tag antenna design. In order to evaluate effects of tag antenna for side view mirror's permittivity as well as car body(conductor), radiation pattern characteristics and readable range have been calculated and measured. The optimized position for a vehicle's RFID system has been observed in the inside of a side mirror and the calculated results show good agreement with the measured results.