• 한국지구과학회지
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• 제34권7호
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• pp.626-632
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• 2013

본 연구에서는 겨울철 특별관측기간(2012년 1월 5일에서 2월 29일)동안 강원지방기상청에 설치된 GPS 자료를 이용하여 가강수량을 산정하고 이를 라디오존데 가강수량 자료와 비교 분석하였다. GPS 자료를 후처리하기 위하여 Bernese 5.0 소프트웨어를 사용하였다. GANG 단독측위와 GANG, DAEJ의 비교적 짧은 거리의 두 지점만을 이용한 상대측위 결과에 따른 가강수량은 시간에 따른 변동폭이 크고 실제 환산된 가강수량에 비해 5배 정도 크게 나타났다. 이러한 대류권 절대 오차에 의한 오류를 제거하기 위한 방법으로 Xian Dao (BJFS), Ibaraki-ken (TSKB) 국제 IGS 사이트의 장거리 기선설정으로 GPS 후처리를 실시한 결과 라디오존데 관측값과 상관이 0.93, 평균편의오차가 0.67, 평균제곱근오차가 6.40 수준으로 나타났다. 또한 GPS 수신기 고도 차이로 발생할 수 있는 대류권 상대 오차를 제거하기위해 강원지방기상청과 아주 가까운 지점인 강릉 원주대학교에 설치된 GPS 자료를 추가하여 후처리한 결과 상관이 0.93, 평균편의오차가 0.61, 평균제곱근오차가 5.79로 보다 개선된 결과를 보였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.235-240
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• 2006

The paper will give an overview of the mission of GalTeC and then concentrate on two main aspects. The first more detailed aspect, is the analysis of the key performance parameters for the Galileo system services and presenting a technical overview of methods and algorithms used. The second more detailed aspect, is the service volume prediction including service dimensioning using the Prediction tool. In order to monitor and validate the Galileo SIS performance for Open Service (OS) and Safety Of Life services (SOL) regarding the key performance parameters, different analyses in the SIS domain and User domain are considered. In the SIS domain, the validation of Signal-in-Space Accuracy SISA and Signal-in-Space Monitoring Accuracy SISMA is performed. For this purpose first of all an independent OD&TS and Integrity determination and processing software is developed to generate the key reference performance parameters named as SISRE (Signal In Space Reference Errors) and related over-bounding statistical information SISRA (Signal In Space Reference Accuracy) based on raw measurements from independent sites (e.g. IGS), Galileo Ground Sensor Stations (GSS) or an own regional monitoring network. Secondly, the differences of orbits and satellite clock corrections between Galileo broadcast ephemeris and the precise reference ephemeris generated by GalTeC will also be compared to check the SIS accuracy. Thirdly, in the user domain, SIS based navigation solution PVT on reference sites using Galileo broadcast ephemeris and the precise ephemeris generated by GalTeC are also used to check key performance parameters. In order to demonstrate the GalTeC performance and the methods mentioned above, the paper presents an initial test result using GPS raw data and GPS broadcast ephemeris. In the tests, some Galileo typical performance parameters are used for GPS system. For example, the maximum URA for one day for one GPS satellite from GPS broadcast ephemeris is used as substitution of SISA to check GPS ephemeris accuracy. Using GalTeC OD&TS and GPS raw data from IGS reference sites, a 10 cm-level of precise orbit determination can be reached. Based on these precise GPS orbits from GalTeC, monitoring and validation of GPS performance can be achieved with a high confidence level. It can be concluded that one of the GalTeC missions is to provide the capability to assess Galileo and general GNSS performance and prediction methods based on a regional and global monitoring networks. Some capability, of which first results are shown in the paper, will be demonstrated further during the planned Galileo IOV phase, the Full Galileo constellation phase and for the different services particularly the Open Services and the Safety Of Life services based on the Galileo Integrity concept.

• Journal of Microbiology
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• 제33권2호
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• pp.136-141
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• 1995

From a cluster of structural rRNA genes which has previsouly been cloned (Hwang and Kim, in submission; J. Microbiol. Biotechnol.), a 1.0-kb Eco RI fragment of DNA which shows significant homology to the 25S and rRNA s of Tricholoma matsutake was used for sequence analysis. Nucleotide sequence was bidirectionally determined using delection series of the DNA fragment. Comparing the resultant 1016-base sequence with sequences in the database, both the 3'end of 25S-rRNA gene and 5S rRNA gene were searched. The 5S rRNA gene is 118-bp in length and is located 158-bp downstream of 3'end of the 25S rRNA gene. IGSI and IGS2 (partial) sequences are also contained in the fragment. Multiple alignment of the 5S rRNA sequences was carried out with 5S rRNA sequences from some members of the subdivision Basidiomycotina obtained from the database. Polygenetic analysis with distance matrix established by Kimura's 2-parameter method and phylogenetic tree by UPGMA method proposed that T. matsutake is closely related to efibulobasidium allbescens. Secondary structure of 5S rRNA was also hypothesized to show similar topology with its generally accepted eukaryotic counterpart.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.178-181
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• 2005

The positioning accuracy of the Global Positioning System (GPS) has been improved considerably during the past two decades. The main error sources such as ionospheric refraction, orbital uncertainty, antenna phase center variation, signal multipath, and tropospheric delay have been reduced substantially, if not eliminated. In this study, the GPS data collected by the GPS receivers that were established as continuously operating reference stations by International GNSS Service (IGS), Ministry of the Interior (MOl), Central Weather Bureau (CWB), and Industrial Technology Research Institute (ITRI) Of Taiwan are utilized to investigate the impact of atmospheric water vapor on GPS positioning determination. The surface meteorological measurements that were concurrently acquired by instruments co-located with the GPS receivers include temperature, pressure and humidity data. To obtain the influence of the GPS height on the proposed impact study. A hydrodynamic ocean tide model (GOTOO.2 model) and solid earth tide were used to improve the GPS height. The surface meteorological data (pressure, temperature and humidity) were introduced to the data processing with 24 troposphere parameters. The results from the studies associated with different GPS height were compared for the cases with and without a priori knowledge of surface meteorological measurements. The finding based on the measurements in 2003 is that the surface meteorological measurements have an impact on the GPS height. The associated daily maximum of the differences is 1.07 cm for the KDNM station. The impact is reduced due to smoothing when the average of the GPS height for the whole year is considered.

• 항공우주산업기술동향
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• 제8권1호
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• pp.77-85
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• 2010

현재 GPS 위성항법시스템은 모두 32기의 Block IIA, Block IIR, Block IIR-M 위성으로 운용되고 있으며 12기의 Block IIA 위성은 15년 이상 된 것들이다. 열악한 우주 환경 속에서 장기간 사용된 위성은 고장이 발생하기도 하고, 특히 정밀한 위치와 시각 제공을 위해 탑재된 원자시계의 노후로 인하여 이상 현상이 발생 하기도 한다. 최근 IGS에서 제공하고 있는 Ultra-rapid 위성 시계 예측 정보의 정확도 성능이 떨어지고 있는데, Block IIA 위성 세슘 시계가 외부 환경이나 온도 변화에 쉽게 영향을 받아 안정된 원자시계의 성향을 보이지 않기 때문이다. 이런 노후 된 위성시계의 이상 현상은 GPS를 이용하는 응용분야에서 위치 성능의 저하를 수반한다. 따라서 노후 된 위성 시계의 성질과 이상 현상 등을 살펴보고 이를 감지 및 극복할 수 있는 기술 현황을 소개한다.

• 한국환경과학회지
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• 제14권7호
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• pp.649-655
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• 2005

Microcystis aeruginosa is common form of cyanobacteria (blue-green algae) capable of producing toxic heptapeptide (microcystin) that cause illness or death. The comparison of molecular genetic method with the morphological characteristics of cyanobacteria was conducted. We have designed PCR primers (JJM98F, JJM1141R) for cyanobacterial 16S rRNA and phycocyanin intergenic spacer (PC-IGS) gene domain. To confirm the production of microcystins, PCR primers for the N-methyltransferase (NMT) domain of microcystin synthetase gene mcyA were designed using 21 cyanobacteria strains Most of isolated strains from the Nakdong River was classified as Microcystis aeruginosa and the similarities were $99\%$ with M. aeruginosa AF 139292. $38.1\%$ of isolated strains contained microcystin synthesis gene. NMT (N-methyltransferase) were not detected in isolated strain in several strains, which means non-toxic. However, the NMTs of the strains were detected during the cultivation.

• 한국측량학회지
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• 제39권5호
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• pp.313-319
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• 2021

The national geodetic reference frame of Korea was adopted in 2003, which is referenced to ITRF (International Terrestrial Reference Frame) 2000 at the epoch of January 1, 2002. For precise positioning based on the satellites, it should be thoroughly maintained to the newest global reference frame. Other than plate tectonic motion, there are significant events or changes such as earthquakes, antenna replacement, PSD (Post-Seismic Deformation), seasonal variation etc. We processed three years of GNSS (Global Navigation Satellite System) data(60 NGII CORS stations, 51 IGS core stations) to produce daily solutions minimally constrained to ITRF. From the time series of daily solutions, the sites with unexpected discontinuity were identified to set up an event(mostly antenna replacement). The combined solution with minimum constraints was estimated along with the velocity, the offsets, and the periodic signals. The residuals show that the surrounding environment also affects the time series to a certain degree, thus it should be improved eventually. The transformation parameters to ITRF2014 were calculated with stability and consistency, which means the national geodetic reference frame is properly aligned to the global reference frame.

• Journal of Positioning, Navigation, and Timing
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• 제12권4호
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• pp.423-430
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• 2023

One recent notable method for real-time elimination of ionospheric errors in geodetic applications is the Predicted Global Ionosphere Map (PGIM). This study analyzes the level of accuracy achievable when applying the PGIM provided by the Center for Orbit Determination of Europe (CODE) to the Korean Peninsula region. First, an examination of the types and lead times of PGIMs provided by the International GNSS Service (IGS) Analysis Center revealed that CODE's two-day prediction model, C2PG, is available approximately eight hours before midnight. This suggests higher real-time usability compared to the one-day prediction model, C1PG. When evaluating the accuracy of PGIM by assuming the final output of the Global Ionosphere Map (GIM) as a reference, it was found that on days with low solar activity, the error is within ~2 TECU, and on days with high solar activity, the error reaches ~3 TECU. A comparison of the errors introduced when using PGIM and three solar activity indices-Kp index, F10.7, and sunspot number-revealed that F10.7 exhibits a relatively high correlation coefficient compared to Kp-index and sunspot number, confirming the effectiveness of the prediction model.

• Journal of Positioning, Navigation, and Timing
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• 제13권2호
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• pp.159-165
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• 2024

The Global Navigation Satellite System (GNSS) has been used as a tool to accurately extract the Total Electron Content (TEC) in the ionosphere. The multi-GNSS (GPS, GLONASS, BeiDou, Galileo, and QZSS) constellations bring new opportunities for ionospheric research. In this study, we develop a regional ionospheric TEC model using GPS, Galileo, and QZSS measurements. To develop an ionospheric model covering the Asia-Oceania region, we select 13 International GNSS Service (IGS) stations. The ionospheric model applies the spherical harmonic expansion method and has a spatial resolution of 2.5°×2.5° and a temporal resolution of one hour. GPS TEC, Galileo TEC, and QZSS TEC are investigated from January 1 to January 31, 2024. Different TEC values are in good agreement with each other. In addition, we compare the QZSS(J07) TEC and the Center for Orbit Determination in Europe (CODE) Global Ionosphere Map (GIM) TEC. The results show that the QZSS TEC estimated in the study coincides closely with the CODE GIM TEC.

• 대한공간정보학회지
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• 제22권1호
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• pp.47-54
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• 2014

휴대용 단말에 간편하게 구현 가능하도록 GPS의 코드의사거리 관측치 기반의 정밀단독측위(PPP; Precise Point Positioning) 알고리즘을 개발하고 그 성능을 검증하였다. PPP에 필요한 기본 모델로 그룹 딜레이, 상대성 효과, 위성안테나 위상중심오프셋 보정모델을 적용하였다. 위성 궤도와 시계오차는 IGS(International GNSS Service) 공식 산출물에 최적의 알고리즘을 통해 보간하고, 대류권과 전리층 오차는 각각 과학기술용 GPS 자료처리 소프트웨어로 산출한 참값과 GIM(Global Ionosphere Model)을 사상함수를 적용해 시선방향 오차로 변환해 적용하였다. 개발된 알고리즘을 4일간 테스트한 결과 수평오차는 0.8~1.6m, 수직오차는 1.6~2.2m 수준으로 나타났다. 이는 DGPS 측위결과와 유사한 성능으로 향후 PPP 알고리즘의 추가개선이 이루어질 경우 다양한 측량 및 위치기반서비스 분야에 활용 가능할 것으로 기대된다.