• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1937-1940
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• 2008

The P1 duplex of Tetrahymena group I ribozyme is the important system for studying the conformational changes in folding of ribozyme. The formation of the P1 duplex between IGS and substrate RNA and the catalytic activity of ribozyme require a variety of metal ions such as $Mg^{2+}$ and $Mn^{2+}$. In order to investigate the effect of the $Mg^{2+}$ concentration on the conformation of the P1 duplex, the NMR study was performed as a function of $Mg^{2+}$ concentration. This study revealed that the less stable AU-rich region formed duplex at $50{^{\circ}C}$ under high $Mg^{2+}$ concentration condition but melts out under low $Mg^{2+}$ concentration condition. It was also found that in the active conformation under 10 mM $MgCl_2$ condition, the unstable central G${\cdot}$U wobble pair maintains the significant base pairing up to $50{^{\circ}C}$. This study provides the information of the unique feature of the P1 duplex structure and the roll of $Mg^{2+}$ ion on the formation of the active conformation.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.36.1-36.1
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• 2010

GNSS(Global Navigation Satellite System)의 하나인 GPS(Global Positioning System)를 이용한 정밀 측위에 있어서 위성의 시계오차는 측위 정확도에 매우 큰 영향을 미친다. GPS위성에는 세슘(Cs)과 루비듐(Rb)으로 이루어진 4개의 원자시계가 탑재되어있으며 현재 사용하고 있는 원자시계의 종류는 NANU(GPS Notice Advisory to Navster Users) 정보를 통해 알 수 있다. 이 연구에서는 IGS(International GNSS Service)에서 제공하는 sp3 파일과 clk 파일을 이용하여 위성시계 특성을 분석하였다. 2000년부터 2009년까지의 sp3 파일에서 각 PRN에 대한 위성시계오차 값을 추출하여 그래프로 분석하였다. 그 결과 대부분의 세슘시계는 직선형태, 루비듐시계는 곡선형태의 특성을 보였으나 일정한 경향은 나타나지 않음을 알 수 있었다. 또한 3주간의 clk 파일에서 위성시계오차 값을 추출하여 각 PRN별로 1차식과 2차식으로 접합(fitting)하고 그 결과를 비교하였다. 세슘시계의 위성시계오차 값의 경우 2차식보다 1차식이 추출 데이터와 일치함을 알 수 있었으며 세슘시계의 위성시계오차 값은 직선형태의 특성을 보이는 것을 확인 할 수 있었다. 그리고 Modified Allan Deviation(MADEV) 방법을 적용하여 분석한 결과 GPS 위성의 block 별로 서로 다른 특성이 보임을 확인할 수 있었다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.3
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• pp.237-247
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• 2011

As of 2011, 72 Permanent GPS Stations are installed to control DGPS reference points by the National Geographic Information Institute in South Korea. As the center of the Earth's mass continues to move, the coordinates of the permanent GPS stations become inconsistent over time. Thus, a reference frame using a set of coordinates and their velocities of a global network of stations at a specific period has been used to solve the inconsistency. However, the relative movement of the permanent GPS stations can lower the accuracy of GPS relative positioning. In this research, we first analyzed the data collected daily during the past 30 months at the 40 permanent GPS stations within South Korea and the 5 IGS permanent GPS stations around the Korean Peninsula using a global network adjustment. We then calculated the absolute and relative amount of movement of the GPS permanent stations. We also identified the optimum renewal period of the permanent GPS stations considering the accuracy of relative GPS surveying. Finally, we developed a Korean a Korean crustal movement model that can be used to improvement of accuracy.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.6
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• pp.563-571
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• 2010

The GPS satellite has three or four atomic clocks that consist of cesiums and rubidiums and the NANU messages can be used to identify the kind of the onboard atomic clock because they classify the clock type on a daily basis. In this study, for long-term analysis of the GPS satellite clock behavior, we extracted satellite clock errors for every PRN from years 2001 through 2009 using the SP3 files that are provided by the IGS. As a result, the cesium clock offsets usually have a linear trend of drifting. On the other hand, rubidium offsets show curvilinear variations in general, even though they cannot be represented as anyone specific polynomial function. For short-term analysis, we extracted satellite clock errors for each PRN for a week-long period using the CLK files that are also provided by the IGS and curve-fitted them with first-order and second-order polynomial functions. In cases of cesium clock errors, they were well-represented by first-order polynomial functions and rubidium clock errors were similar with second-order polynomials. However, some of rubidium clock errors could not be represented as any polynomial fitting function. To analyze the characteristic of GPS satellite by each block and atomic clock, we applied Modified Allan Deviation criterion to the dataset from years 2007 and 2010. We found that the Modified Allan Deviation characteristics changed significantly according the block and atomic clock type.

• Journal of Astronomy and Space Sciences
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• v.20 no.1
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• pp.1-10
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• 2003

A precise kinematic orbit determination (P-KOD) procedure for Low Earth Orbiter(LEO) using the GPS ion-free triple differenced carrier phases is presented. Because the triple differenced observables provide only relative information, the first epoch's positions of the orbit should be held fixed. Then, both forward and backward filtering was executed to mitigate the effect of biases of the first epoch's position. p-KOD utilizes the precise GPS orbits and ground stations data from International GPS Service (IGS) so that the only unknown parameters to be solved are positions of the satellite at each epoch. Currently, the 3-D accuracy off-KOD applied to CHAMP (CHAllenging Min-isatellite Payload) shows better than 35 cm compared to the published rapid scientific orbit (RSO) solution from GFZ (GeoForschungsZentrum Potsdam). The data screening for cycle slips is a particularly challenging procedure for LEO, which moves very fast in the middle of the ionospheric layer. It was found that data screening using SNR (signal to noise ratio) generates best results based on the residual analysis using RSO. It is expected that much better accuracy are achievable with refined prescreening procedure and optimized geometry of the satellites and ground stations.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.116.1-116
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• 2003

Fusarium oxysporum f. sp. fragariae is a fungal pathogen causing wilt disease on strawberry. The RAPD and RFLP of IGS region of rDNA were used to identify genetic affinity among 22 isolates of F. oxysporum f. sp. fagariae obtained from various location of major strawberry cultivating areas in Korea. Approximately 2.6kb DNA fragment was amplified with primer CNS1 and CNL12, and polymorphisms were observed with Avail and HinfI. A dendrogram was constructed using the UPGMA for cluster analysis. Eight distinct groups were clustered based on the banding pattern obtained from RAPD and rDNA RFLP. There was high level genetic variation among Korean isolates of Fusarium of sporum f. sp. fragariae.

• Journal of Korean Society for Geospatial Information Science
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• v.7 no.1 s.13
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• pp.11-20
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• 1999

To establish the basis of GPS network for the perception of diastrophism, we slected 7 stations(baseline $100{\sim}300km$) all around south Korea considering the earthquake and the satellites all-in-view. As a result of periodical measurement, the change of relative positions between selected stations in Korea was very small. We could know that the baseline between Korea and Japan are decreasing by a few centimeters, as one of the results of analysing baseline vector changes by continuous measuring IGS stations and Korea(KAMC) station.

• Journal of Microbiology and Biotechnology
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• v.11 no.3
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• pp.515-523
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• 2001

The dinoflagellates have some primitive nuclear features and are evolutionarily intermediate between prokaryotes and eukaryotes. The small subunit ribosomal RAN gene, the 5.8S ribosomal RNA gene, and the internal transcribed spacer (ITS) of Gonyaulax polyedra were cloned, and their sequences were analyzed to better understand their evolutionary position. The small subunit ribosomal RNA gene was 1,794 nt long, the large subunit ribosomal RNA gene was approximately 3,500 nt long, and the 5.8S ribosomal RNA gene was 159 nt long. The first internal transcribed spacer (ITS1) was 191 nt long, and the second internal transcribed spacer (ITS2) was 185 nt long. The intergenic spacer of the ribosomal RNA gene (IGS) was about 2,200 nt long, indicating that 5,800 nt of transcribed sequences were separated by roughly 2,200 nt of intergenic spacer. The ribosomal RNA genes were repeated many times and arranged in a head-to-tail, tandemly repeated manner. The repeating unit of ribosomal RNA gene of G. polyedra was proposed to be 8,000 nt long. Based on the lengths of ribosomal RNA, sequence alignments with representative organisms, and phylogenetic analysis on ribosomal RNA, G. polyedra appears to be one of the alveolates branched from the eukaryotic crown and, among dinoflagellates, it seems to not have emerged early.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.4
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• pp.155-161
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• 2014

The purpose of this study is to develop precise point positioning (PPP) algorithms based on GLONASS code-pseudorange, verify their performance and present their utility. As the basic correction models of PPP, we applied Inter Frequency Bias (IFB), relativistic effect, satellite antenna phase center offset, and satellite orbit and satellite clock errors, ionospheric errors, and tropospheric errors that must be provided on a real-time basis. The satellite orbit and satellite clock errors provided by Information-Analytical Centre (IAC) are interpolated at each observation epoch by applying the Lagrange polynomial method and linear interpolation method. We applied Global Ionosphere Maps (GIM) provided by International GNSS Service (IGS) for ionospheric errors, and increased the positioning accuracy by applying the true value calculated with GIPSY for tropospheric errors. As a result of testing the developed GLONASS PPP algorithms for four days, the horizontal error was approximately 1.4 ~ 1.5 m and the vertical error was approximately 2.5 ~ 2.8 m, showing that the accuracy is similar to that of GPS PPP.

• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.30-34
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• 2012

National Meteorological Satellite Center(NMSC) of Korea Meteorological Administration(KMA) has launched to implement the application development to get prepared for the space weather operation since 2010. As a action of KMA's space weather work, NMSC constructed Global Navigation Satellite System(GNSS) application system for meteorology and space weather. We will introduce NMSC's space weather application system which derives regional TEC(Total Electron Content) in near real time using nation-wide GNSS network data. First, We constructed system for collecting GNSS data, which is currently collecting about 80 stations operated by agencies like NGII(National Geographic Information Institute), Central Office of DGPS(Differential GPS), and KASI(Korea Astronomy and Space Science) including KMA's own data of 2 stations. In order to retreive regional TEC over Korean peninsular, we build up the automatic processes running every 1-hour. In these processes, firstly, GNSS data of every stations with 24 hours time window are processed to derive DCBs(Differential Code Biases) of each GNSS station and TEC values on every ionosphere piercing point(IPP). Then we made gridded regional TEC map with resolution of 0.25 degree from 31N, 121E to 41N, 135E by combination of all station results within 30 minutes window with assumption that TEC of a given point during a given 30 minutes window would have a constant value. The grid points without TEC value are interpolated using Barnes objective analysis. We presentour regional TEC maps, which can describe better on the status of ionosphere over Korean peninsular compared to IGS TEC maps.