Korea Multi-Purpose Satellite Research Articles

Radiometric characterization and validation for the KOMPSAT-3 sensor

A radiometric characterization of the Korea Multi-Purpose Satellite (KOMPSAT) Series multispectral imagery was performed by the Korea Aerospace Research Institute (KARI) and the Pukyong National University Remote Sensing Group (PKNU RSG). This paper presents a vicarious radiometric calibration performed by KARI and PKNU RSG in 2012 and 2014. Correlations between top-of-atmosphere (TOA) radiances and the spectral band responses of the KOMPSAT-3 sensors at Zuunmod, Mongolia and Goheung, South Korea, were significant for multispectral bands. KOMPSAT-3 calibration coefficients for all bands estimated in 2012 continued to agree well with calibration coefficients estimated in 2014 (within 1.5%). As a result of this study, KARI will update and publish the KOMPSAT-3 multispectral radiometric calibration coefficients as official values. The average difference in TOA reflectance between KOMPSAT-3 and Landsat-8 images over the Libya 4, Libya and Railroad Valley Playa, USA, in the red–green–blue region was under 3%, whereas in the near-infrared band, the TOA reflectance of KOMPSAT-3 was lower than that of Landsat-8 due to the difference in the bandwidths of two sensors. The KOMPSAT-3 sensor includes a bandwidth near 940 nm that can be strongly absorbed by water vapour and therefore displayed low reflectance.

Comparison of SWAT streamflow and water quality in an agricultural watershed using KOMPSAT-2 and Landsat land use information

This study investigated streamflow and water quality using the Soil and Water Assessment Tool (SWAT) and by applying two land use datasets from KOrea Multi-Purpose SATellite (KOMPSAT)-2 and Landsat TM (Thematic Mapper) images. For a 262.3 km2 agricultural watershed located in the northwest part of South Korea, the Landsat TM and KOMPSAT-2 could produce 8 and 25 land use classes from spatial resolutions of 30 m and 2 m, respectively. For each land use condition, the SWAT model was calibrated and validated using 8 years (2000-2007) of daily streamflow and monthly sediment, Total Nitrogen (T-N), and Total Phosphorous (T-P) data. The average Nash-Sutcliffe model Efficiencies (NSEs) of streamflow for KOMPSAT-2 and Landsat were 0.80 and 0.71, respectively. The average NSEs of sediment, T-N, and T-P were 0.52, 0.97, and 0.67 for KOMPSAT-2 and 0.30, 0.77, and 0.35 for Landsat, respectively. From the difference in the areal statistics and distribution between the two land uses, the key parameter for streamflow calibration was SCS-CN (Soil Conservation Service-CN). The watershed average SCS-CN value from KOMPSAT-2 was 1.05-fold greater than that from Landsat TM. The larger SCS-CN value increased the surface runoff and subsequently increased the sediment, T-N and T-P transport in the stream.

Automatic cloud detection for high spatial resolution multi-temporal images

In this article, we propose an automatic cloud detection process for images with high spatial resolution. First, thick cloud regions are detected by applying a simple threshold method to the target image (an image that includes a cloud-covered region). Next, a reference image (another image that was acquired at a different time and includes the region with relatively little or no cloud-cover) is transformed to the coordinates of the target image by a modified scale-invariant feature transform (SIFT) method. The difference between the target image and transformed reference image is used to extract the peripheral cloud regions. The thick and peripheral cloud regions are then merged based on their relative locations and areas to detect the final cloud regions. Multi-temporal Korea Multi-Purpose Satellite-2 (KOMPSAT-2) images are used to construct study sites to evaluate the proposed method for a range of cloud-cover cases. From the proposed method, a large number of correctly matched points were extracted for this generation of the transformation model, and cloud-covered regions were effectively detected for all sites without manual intervention.

현업용 기상위성에 대한 주도권 다툼: 1960년 TIROS 발사 이후

Abstract Currently, Korea is developing a Cheollian follow-on satellite program, named asGeostationary Korea Multipurpose Satellite 2 (GK-2), which consists of two satellites. One satel-lite (GK-2A) is dedicated to the meterological mission, while the second one (GK-2B) hosts twomain payloads for the ocean and environmental application. As GK-2A is dedicated to the meteo-rological mission unlike Cheollian, there have been discussions on the possibility of transferringthe responsibilities of the GK-2A program to the Korea Meteorological Administration. To helpresolve any consumptive disputes or to find an efficient way for the GK-2A program, the eventshappened after the successful launch of the first meteorological satellite TIROS-1 in the U.S. inApril 1960 are investigated. With the successful demonstration of usefulness of TIROS-1 for themeteorological applications, organizations such as the Weather Bureau and the Department ofDefense, responsible for the real time application of the TIROS 1 data, strongly requested for anoperational meteorological satellite program which resulted in the plan for the National Opera-tional Meteorological Satellite System (NOMSS). The plan was strongly supported by KennedyAdminstration and was put forwarded for the new program under the responsibility of WeatherBureau to the Congress. However, the responsible Committee on Science and Aeronautics sidedwith NASA and requested major revision of the responsibility. Due to many unfavorable condi-tions, Weather Bureau accepted the requests and signed with NASA on the agreement for theoperational meteorological satellite. However, with the delay of Nimbus satellite which is plannedto be used for the prototype of the operational satellite and changes of the unfavorable situations,the Weather Bureau could draw a second agreement with NASA. The new agreement reflectedmost propositions requested by the Weather Bureau for the NOMSS plan. Until now the secondagreement is regarded as the basic principles for the operational meteorological satellite programin the U.S. This study investigates the backgrounds and processes of the second agreement and itsimplications for the GK-2 program.Key words: National operational meteorological satellite system, agreement between theweather bureau and NASA, TIROS-1, geostationary Korea multipurpose satellite

Validation of an active transponder for KOMPSAT-5 SAR image calibration

This paper describes the development and validation of a transportable active transponder designed for the image calibration of Korea Multi-Purpose Satellite-5 (KOMPSAT-5) with a synthetic aperture radar (SAR). Ground targets are essential in SAR image calibration. The environment for the deployment of ground targets for SAR image calibration should provide uniformity and minimum interference. The Amazon or deserts are regarded as desirable environments. However, such environments for SAR image calibration are difficult to find in Korea. Thus, it will be advantageous to have an active transponder whose performance will not be severely limited by the absence of such uniform environment. We have therefore developed an active transponder which has an adjustable internal delay and into which the orbit data of an arbitrary satellite can be loaded. The stored obit data with the aid of an internal global positioning system (GPS) receiver and gyroscope enables the active transponder to point to a selected satellite. In addition, a virtual deployment of the active transponder is possible due to its adjustable internal delay. Thus, the developed active transponder can be deployed at any place without environmental constraint. The performance of the developed active transponder is validated using the satellite TerraSAR-X, which is already in operation. The test results show that the active transponder is successfully compliant with the requirements for KOMPSAT-5 image calibration.

다목적실용위성 5호의 SAR 영상 검·보정을 위한 이동형 능동 트랜스폰더 개발

다목적실용위성 5호는 영상 레이더(SAR: Synthetic Aperture Radar)을 탑재하여 야간이나 구름이 있는 지역에 대해서도 지속적인 영상촬영이 가능하다. 발사 후 초기 운영 시험에서는 SAR 탑재체에 의해 관측된 영상에 대한 기하 및 복사 보정을 수행한다. 이러한 보정은 지표상의 위치 및 RCS(Radar Cross Section)을 알고 있는 보정장치에서 반사된 SAR 신호에 의해 나타난 영상 픽셀에서의 위치 및 값을 이용하여 처리된다. 이러한 보정을 위해 기존 반사기와 달리 능동 트랜스폰더는 RCS 값을 변경할 수 있으며, 내부 시간 지연 기능에 의해 가상의 위치로 이동하는 효과를 영상에서 나타낼 수 있다. 본 논문에서는 능동 트랜스폰더의 개발에 필요한 요구사항을 도출하여 이로부터 설계, 조립 및 시험결과를 정리하였다. KOMPSAT-5(KOrea Multi-Purpose SATellite-5) has a benefit of continuously conducting its mission in all weather and even night by loading SAR(Synthetic Aperture Radar) payload, which is different from optical sensor of KOMPSAT-2 satellite. During IOT(In-Orbit Test) periods, SAR image calibration should be conducted through ground target of which location and RCS is pre-determined. Differently from the conventional corner reflector, active transponder has a capability to change its internal transfer gain and delay, which allows active transponder to be shown in a pixel of SAR image with very high radiance and virtual location. In this paper, the development of active transponder is presented from design to I&T(Integration and Test).

Efficient edge-directed deblocking algorithm for KOMPSAT-2 satellite images

In this paper, we present a deblocking algorithm that removes grid and staircase artefacts, which result from the compression of images. The KORea Multi-Purpose SATellite-2 images are efficiently compressed using an algorithm that assigns quantisation coefficients, by rows, according to local region complexity, in such a way that more complicated regions are more compressed. However, this approach is problematic in that it produces blocking artefacts in those relatively less complicated areas within the same row as the complicated regions. Removing these artefacts with a general deblocking algorithm can, undesirably, blur the complicated regions as well as the artefacts; additionally, the general filter is poor at preserving curved edges. Therefore, the algorithm proposed herein presents an adaptive filtering scheme for removing blocking artefacts while preserving image details, including curved edges, using a content analysis. Particularly, edge adaptive filtering has been introduced to remove staircase artefacts around the big image edges. Experimental analyses revealed that the proposed method outperforms several state-of-the-art approaches in terms of subjective or objective image quality, and computational speed.

저궤도 다중위성 운용을 위한 매트릭스 구조의 수신 채널 구현

다수의 저궤도 위성을 운영하는 경우, 위성별 운영 궤도에 의해서 지리적으로 고정된 하나의 지상국은 2개 이상의 위성과 통신을 해야 하는 상황이 발생된다. 일반적으로 위성에서 관측된 영상 데이터를 수신 및 처리하는 시스템은 위성별로 다를 뿐만 아니라, 1:1 백업 구성을 함으로써 지상 수신 안테나가 한정되어 설치된 지상국에서는 위성의 수가 많아질수록 데이터 전달을 위한 안테나에서 영상 수신 처리 시스템 간의 접속 설계가 복잡해지는 문제가 발생된다. 본 논문에서는 2개의 위성에 대해 동시 운영이 가능하며, 위성별 영상데이터 저장장치를 연결함으로써 확장이 가능한 매트릭스 구조의 수신 채널 구현 내용이 작성되어 있다. 구현된 수신 채널은 다목적실용위성 3호 발사 이후에 운영 검증을 완료하였으며, 확장 기능을 통해 추후 발사될 5호와 3A호에 대해서도 적용할 예정이다. In the case of multi-mission LEO(Low Earth Orbit) operations, depending on the orbit of each satellite, one ground site is supposed to be communicated with more than two satellites at the same time. On top of that, image data processing system is generally mission-specific and 1:1 backup configuration. For the reason, if ground site has smaller number of antenna than that of satellite, interface with image data processing system would be very complicated. In this paper, considering that two LEO satellites can be operating and image data recording unit in redundancy can be easily plug-in, the implementation of matrix receiving structure is described. This matrix receiving structure has been validated from KOMPSAT-2 and -3(KOrea Multi-Purpose SATellite-2 and -3) since KOMPSAT-3 was launched in May, 2012. This structure will be applied for the KOMPSAT-3A and -5 through its expandability.

Fast convergence of orbit determination using geomagnetic field measurement in Target Pointing Satellite

Autonomous and magnetometer-based orbit determination algorithm in target pointing satellite based solely on magnetometer measurements for speeding up filter convergence is proposed. The cosine angle between geomagnetic field vector and target direction vector, as viewed from the satellite, provides some quantity that is sensitive to satellite position, more regular and periodical than the magnetic field magnitude as a satellite moves around its orbit, and easily observable from magnetometers. An algorithm is formulated by applying the unscented Kalman filter (UKF) based on the laws of orbital mechanics, the measurement models of geomagnetic field magnitude and the cosine angle. The algorithm is tested and verified by using real-flight data obtained from Korea Multi-Purpose Satellite-1 (KOMPSAT-1) and Magnetic Field Satellite (MAGSAT). The results obtained from numerical simulations using KOMPSAT-1 and MAGSAT data illustrate the significant convergence speed up and the robustness against both noise and bias of magnetic measurements. The proposed orbit determination is adequate as a primary routine for a target pointing satellite mission that requires fast convergence. Otherwise, it is sufficient as a secondary routine to provide redundancy.

Image collection planning for KOrea Multi-Purpose SATellite-2

This paper studies an image collection planning problem for a Korean satellite, KOMPSAT-2 (KOrea Multi-Purpose SATellite-2). KOMPSAT-2 has the mission goal of maximizing image acquisition in time and quality requested by customers and operates under several complicating conditions. One of the characteristics in KOMPSAT-2 is its strip mode operation, in which segments of continuous-observation areas with known sizes are captured one at a time. In this paper, we regard the segment as a group of adjoining geographical square regions (scenes), whose size must also be determined. Thus, the problem involves the determination of proper segment lengths as well as an image collection schedule. We present a binary integer programming model for this problem in a multi-orbit long-term planning environment and provide a heuristic solution approach based on the Lagrangian relaxation and subgradient methods. We also present the results of our computational experiment based on randomly generated data.

Landslide detection and susceptibility mapping in the Sagimakri area, Korea using KOMPSAT-1 and weight of evidence technique

The purpose of this study is to detect landslide locations from satellite images and use them for landslide susceptibility mapping in the Sagimakri area, Korea using a geographic information system and a data-driven weight of evidence model. The landslide location areas were identified from Korea multipurpose satellite images by means of change detection technique and further verified by extensive field survey. Subsequently, landslide locations were randomly selected in a 70:30 ratio for training and validation of the model, respectively. A spatial database was constructed, which is composed of topography, forest, soil, and land cover, and 14 landslide-related factors were extracted from the database. The relationships between the detected landslide locations and the factors were identified and quantified by weights of evidence model. Tests of conditional independence were performed for the selection of factors, allowing five different combinations of factors to be analyzed. The relationships were used as the contrast values, W + and W − of factor ratings in the overlay analysis to create landslide susceptibility indexes and maps. The results of the analysis were validated by comparison with known landslide locations that were not used directly in the analysis.

Evaluation of ozone profile and tropospheric ozone retrievals from GEMS and OMI spectra

Abstract. South Korea is planning to launch the GEMS (Geostationary Environment Monitoring Spectrometer) instrument into the GeoKOMPSAT (Geostationary Korea Multi-Purpose SATellite) platform in 2018 to monitor tropospheric air pollutants on an hourly basis over East Asia. GEMS will measure backscattered UV radiances covering the 300–500 nm wavelength range with a spectral resolution of 0.6 nm. The main objective of this study is to evaluate ozone profiles and stratospheric column ozone amounts retrieved from simulated GEMS measurements. Ozone Monitoring Instrument (OMI) Level 1B radiances, which have the spectral range 270–500 nm at spectral resolution of 0.42–0.63 nm, are used to simulate the GEMS radiances. An optimal estimation-based ozone profile algorithm is used to retrieve ozone profiles from simulated GEMS radiances. Firstly, we compare the retrieval characteristics (including averaging kernels, degrees of freedom for signal, and retrieval error) derived from the 270–330 nm (OMI) and 300–330 nm (GEMS) wavelength ranges. This comparison shows that the effect of not using measurements below 300 nm on retrieval characteristics in the troposphere is insignificant. However, the stratospheric ozone information in terms of DFS decreases greatly from OMI to GEMS, by a factor of ∼2. The number of the independent pieces of information available from GEMS measurements is estimated to 3 on average in the stratosphere, with associated retrieval errors of ~1% in stratospheric column ozone. The difference between OMI and GEMS retrieval characteristics is apparent for retrieving ozone layers above ~20 km, with a reduction in the sensitivity and an increase in the retrieval errors for GEMS. We further investigate whether GEMS can resolve the stratospheric ozone variation observed from high vertical resolution Earth Observing System (EOS) Microwave Limb Sounder (MLS). The differences in stratospheric ozone profiles between GEMS and MLS are comparable to those between OMI and MLS below ~3 hPa (~40 km), except with slightly larger biases and larger standard deviations by up to 5%. At pressure altitudes above ~3 hPa, GEMS retrievals show strong influence of a priori and large differences with MLS, which, however, can be sufficiently improved by using better a priori information. The GEMS-MLS differences show negative biases of less than 4% for stratospheric column ozone, with standard deviations of 1–3%, while OMI retrievals show similar agreements with MLS except for 1% smaller biases at middle and high latitudes. Based on the comparisons, we conclude that GEMS will measure tropospheric ozone and stratospheric ozone columns with accuracy comparable to that of OMI and ozone profiles with slightly worse performance than that of OMI below ~3 hPa.

Automated HRSI georegistration using orthoimage and SRTM: Focusing KOMPSAT-2 imagery

Conventional manual georegistration has been labor-intensive and time-consuming to process globally acquired high-resolution satellite imagery (HRSI) including the Korea Multi-Purpose Satellite-2 (KOMPSAT-2). While an image-to-image matching-based method can provide an automated procedure, geometric and pixel value differences such as the apparent leaning of the terrain limits an accurate georegistration. This study utilizes the projection of orthoimages into the HRSI space using external elevation data to reduce the geometric difference, and an edge matching is applied to overcome the pixel value differences. Either rigorous or replacement sensor modeling is then carried out for georegistration with robust outlier removal. An experiment for a KOMPSAT-2 strip using Digital Orthophoto Quadrangles and the Shuttle Radar Topography Mission improved the horizontal positional accuracy from 70 to only a few meters for the test data set.

Validation on Residual Variation and Covariance Matrix of USSTRATCOM Two Line Element

Satellite operating agencies are constantly monitoring conjunctions between satellites and space objects. Two line element (TLE) data, published by the Joint Space Operations Center of the United States Strategic Command, are available as raw data for a preliminary analysis of initial conjunction with a space object without any orbital information. However, there exist several sorts of uncertainties in the TLE data. In this paper, we suggest and analyze a method for estimating the uncertainties in the TLE data through mean, standard deviation of state vector residuals and covariance matrix. Also the estimation results are compared with actual results of orbit determination to validate the estimation method. Characteristics of the state vector residuals depending on the orbital elements are examined by applying the analysis to several satellites in various orbits. Main source of difference between the covariance matrices are also analyzed by comparing the matrices. Particularly, for the Korea Multi-Purpose Satellite-2, we examine the characteristics of the residual variation of state vector and covariance matrix depending on the orbital elements. It is confirmed that a realistic consideration on the space situation of space objects is possible using information from the analysis of mean, standard deviation of the state vector residuals of TLE and covariance matrix.

상세 공간정보를 활용한 국지기온 분석 개선 - 서울 은평구 뉴타운을 사례로 -

A higher spatial resolution is preferable to support the accuracy of detailed climate analysis in urban areas. Airborne LiDAR (Light Detection And Ranging) and satellite (KOMPSAT-2, Korea Multi-Purpose Satellite-2) images at 1 to 4 m resolution were utilized to produce digital elevation and building surface models as well as land cover maps at very high(5m) resolution. The Climate Analysis Seoul(CAS) was used to calculate the fractional coverage of land cover classes in built-up areas and thermal capacity of the buildings from their areal volumes. It then produced analyzed maps of local-scale temperature based on the old and new input data. For the verification of the accuracy improvement by the precise input data, the analyzed maps were compared to the surface temperature derived from the ASTER satellite image and to the ground observation at our detailed study region. After the enhancement, the ASTER temperature was highly correlated with the analyzed temperature at building (BS) areas (R

아리랑위성 2호 입체영상을 이용한 지도제작 가능성 연구

The KOrea Multi-Purpose SATellite(KOMPSAT)-2 has a capability to provide a cross-track stereo imagery using two different orbits for generating various spatial information. However, in order to fully realize the potential of the KOMPSAT-2 stereo imagery in terms of mapping, various tests are necessary. The purpose of this study is to evaluate the possibility of mapping using the KOMPSAT-2 stereo imagery. For this, digital plotting was conducted based on the stereoscopic images. Also the Digital Elevation Model(DEM) and an ortho-image were generated using digital plotting results. An accuracy of digital plotting, DEM, and ortho-image were evaluated by comparing with the existing data. Consequently, we found that horizontal and vertical error of the modeling results based on the Rational Polynomial Coefficient(RPC) was less than 1.5 meters compared with the Global Positioning System(GPS) survey results. The maximum difference of vertical direction between the plotted results in this study and the existing digital map on the scale of 1/5,000 was more than 5 meters according as the topographical characteristics. Although there were some irregular parallax on the images, we realized that it was possible to interpret and plot at least seventy percent of the layer which was required the digital map on the scale of 1/5,000. Also an accuracy of DEM, which was generated based on the digital plotting, was compared with the existing LiDAR DEM. We found that the ortho-images, which were generated using the extracted DEM in this study, sufficiently satisfied with the requirement of the geometric accuracy for an ortho-image map on the scale of 1/5,000.

A shape–size index extraction for classification of high resolution multispectral satellite images

We propose a new spatial feature extraction method for supervised classification of satellite images with high spatial resolution. The proposed shape–size index (SSI) feature combines homogeneous areas using spectral similarity between one central pixel and its neighbouring pixels. A spatial index considers the shape and size of the homogeneous area, and suitable spatial features are parametrically selected. The generated SSI feature is integrated with the original high resolution multispectral bands to improve the overall classification accuracy. A support vector machine (SVM) is employed as a classifier. In order to evaluate the proposed feature extraction method, KOMPSAT-2 (Korea Multipurpose Satellite 2), QuickBird-2 and IKONOS-2 high resolution satellite images are used. The experiments show that the SSI algorithm leads to a notable increase in classification accuracy over the grey level co-occurrence matrix (GLCM) and pixel shape index (PSI) algorithms, and an increase when compared with using multispectral bands only.

GPS-Based Orbit Determination for KOMPSAT-5 Satellite

Korea Multi-Purpose Satellite-5 (KOMPSAT-5) is the first satellite in Korea that provides 1 m resolution synthetic aperture radar (SAR) images. Precise orbit determination (POD) using a dual-frequency IGOR receiver data is performed to conduct high-resolution SAR images. We suggest orbit determination strategies based on a differential GPS technique. Double-differenced phase observations are sampled every 30 seconds. A dynamic model approach using an estimation of general empirical acceleration every 6 minutes through a batch least-squares estimator is applied. The orbit accuracy is validated using real data from GRACE and KOMPSAT-2 as well as simulated KOMPSAT-5 data. The POD results using GRACE satellite are adjusted through satellite laser ranging data and compared with publicly available reference orbit data. Operational orbit determination satisfies 5 m root sum square (RSS) in one sigma, and POD meets the orbit accuracy requirements of less than 20 cm and 0.003 cm/s RSS in position and velocity, respectively.

RPC를 기반으로 한 아리랑 2호 에피폴라 영상제작

As high-resolution satellite images have enabled large scale topographic mapping and monitoring on global scale with short revisit time, agile sensor orientation, and large swath width, many countries make effort to secure the satellite image information. In Korea, KOMPSAT-2 (KOrea Multi-Purpose SATellite-2) was launched in July 28 2006 with high specification. These satellites have stereo image acquisition capability for 3D mapping and monitoring. To efficiently handle stereo images such as stereo display and monitoring, the accurate epipolar image generation process is prerequisite. However, the process was highly limited due to complexity in epipolar geometry of pushbroom sensor. Recently, the piecewise approach to generate epipolar images using RPC was developed and tested for in-track IKONOS stereo images. In this paper, the piecewise approach was tested for KOMPSAT-2 across-track stereo images to see how accurately KOMPSAT-2 epipolar images can be generated for 3D geospatial applications. In the experiment, two across-track stereo sets from three KOMPSAT-2 images of different dates were tested using RPC as the sensor model. The test results showed that one-pixel level of y-parallax was achieved for manually measured tie points.

Precision Assessment of Near Real Time Precise Orbit Determination for Low Earth Orbiter

Department of Electronics Engineering, Chung-Nam National University, Daejeon 305-764, KoreaThe precise orbit determination (POD) of low earth orbiter (LEO) has complied with its required positioning accuracy by the double-differencing of observations between International GNSS Service (IGS) and LEO to eliminate the common clock error of the global positioning system (GPS) satellites and receiver. Using this method, we also have achieved the 1 m positioning accuracy of Korea Multi-Purpose Satellite (KOMPSAT)-2. However double-differencing POD has huge load of processing the global network of lots of ground stations because LEO turns around the Earth with rapid velocity. And both the centimeter accuracy and the near real time (NRT) processing have been needed in the LEO POD applica-tions--atmospheric sounding or urgent image processing--as well as the surveying. An alternative to differential GPS for high accuracy NRT POD is precise point positioning (PPP) to use measurements from one satellite receiver only, to re-place the broadcast navigation message with precise post processed values from IGS, and to have phase measurements of dual frequency GPS receiver. PPP can obtain positioning accuracy comparable to that of differential positioning. KOMPSAT-5 has a precise dual frequency GPS flight receiver (integrated GPS and occultation receiver, IGOR) to satisfy the accuracy requirements of 20 cm positioning accuracy for highly precise synthetic aperture radar image processing and to collect GPS radio occultation measurements for atmospheric sounding. In this paper we obtained about 3-5 cm positioning accuracies using the real GPS data of the Gravity Recover and Climate Experiment (GRACE) satellites loaded the Blackjack receiver, a predecessor of IGOR. And it is important to reduce the latency of orbit determination processing in the NRT POD. This latency is determined as the volume of GPS measurements. Thus changing the sampling intervals, we show their latency to able to reduce without the precision degradation as the assessment of their precision.