• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.327-332
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• 2022

The Korea Augmentation Satellite System (KASS) is the Satellite-Based Augmentation System (SBAS) under development in Korea. KASS navigation service support navigation Safety of Life (SoL) service. KASS signal provides corrections to Global Positioning System (GPS) data received from KASS Reference Stations (KRS) and is broadcast form Geostationary Earth Orbiting (GEO) satellites to KASS users and is used by GPS/SBAS user equipment to improve the accuracy, availability, continuity and integrity of the navigation solution. Seven KRS's collect the satellite data and send them to the KASS Processing Stations (KPS) for the generation of the corrections and the monitoring the integrity. For performing its computation the KPS needs to know accurate and reliable KRS antennas coordinates. These coordinates are provided as configuration parameters to the KPS. This means that the reference frame in which the KPS work is the one represented by the set of coordinates provided as input. Therefore, the activity to maintain the accuracy of the KRS antenna coordinates is necessary, knowing that coordinates can evolve due to earth plates movements or earthquakes. In this paper, we analyzed the geodetic survey results for KRS antenna coordinates from Site Acceptance Test (SAT) #1 in December 2020 to August 2022. In the future, it is expected that these activities and planning for KRS coordinates maintenance will be produced and provided to KASS system operators for KPS configuration updates during the KASS lifetime of 15 years. Through these maintenance activities, it is expected that monitoring and analysis of unpredictable events such as earthquakes and seism will be possible in the future.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.96-104
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• 2018

NOTAM is an announcement that is distributed to flight attendants with status information related to aviation. ICAO, the International Civilian Aviation Organization, recommends that a NOTAM service be provided for the SBAS service in order to use the SBAS signal-based access procedure. To comply with ICAO recommendation, KASS must provide NOTAM service to all aircraft landing using SBAS signal in order to provide APV-I SoL service. Therefore, it is necessary to develop KASS NOTAM system to provide KASS NOTAM service. In this paper, we analyzed the regulations related to NOTAM in Korea and abroad and analyzed the present state of NOTAM service in Korea. Based on this, we propose a method of providing KASS NOTAM service. We analyzed the NOTAM system of WAAS in the US and EGNOS in Europe and analyzed the main functional requirements of the KASS NOTAM system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.1
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• pp.49-61
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• 2015

Ground Based Augmentation System(GBAS) is a system that offers an aircraft within 23 NM radius from the airport precision positioning service and precision approach service using the concept of Differential Global Positioning System(DGPS). After GBAS ground equipment installing at the airport, functionalities and performances of GBAS should be verified through the GBAS ground and flight testing. This paper describes the methods and results for GBAS flight test using the flight inspection aircraft at Gimpo International Airport. From the test results, we confirmed that the VDB data was received without misleading within the VDB coverage of Gimpo International Airport, and VDB field strength, protection level, and course alignment accuracy met the evaluation's criteria.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.1
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• pp.83-89
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• 2023

The Korea Augmentation Satellite System (KASS) system is a Satellite Based Augmentation System (SBAS) under development to provide APV-I SBAS service in the Republic of Korea. The KASS ground segment generates correction and integrity information for GPS measurements of KASS users using the accurate positions of KASS Reference Station (KRS) antenna phase centers. For this reason, the accuracy of KRS reference points through geodetic survey campaigns is one of the important factors for providing the KASS service in compliance with the required navigation performance. In order to obtain accurate positions, two geodetic survey campaigns were performed at several reference points, such as Mark, Center of Mast at Ground Level (CMGL), and Center of Hole in Top Plate (CHTP), of each KRS site using three different survey methods, the Virtual Reference Station (VRS), Flächen Korrektur Parameter (FKP), and raw data post-processing methods. By comparing and analyzing the results, the computed coordinates of the reference points were verified and Antenna Phase Center (APC) positions were calculated using KRS Antenna Reference Point (ARP) data, and the first KASS Site Acceptance Test (SAT#1) was performed successfully using the verified APC coordinates. After the first site survey activities, the KASS operators should maintain the coordinates with the required performance such that the overall KASS navigation performance commitment is guaranteed during the lifetime of 15 years. Therefore, the maintenance plan for the KRS antenna coordinates should be developed before the commissioning of KASS operation planned after 2023. Therefore, this paper presents a geodetic survey method selected for the maintenance activities and provides the rationale for using this method.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2768-2774
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• 2011

In this paper, we investigate the methods to improve the position accuracy using DGNSS(Differential Global Navigation Satellite System). Then we configure the real-time DGNSS environment with use of GPS and MSAS as SBAS(Satellite Based Augmentation System) currently being in service by Japan. And we verify the improvement of position accuracy and the continuity of GPS correction data through the realtime DGNSS test in Joongang line, Kyungbu line, Honam line.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.458-463
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• 1997

In this paper, we propose a variable structure control approach for the system with matched and unmatched uncertainty. By using time-varying sliding mode, the reaching mode is removed, and the design methodology represents a realistic design approach with quadratic criterion for systems incorporating both matched and unmatched uncertainties. The criterion contains states and linear part of input for all time. The practical application of the control strategy is presented in the design of a stability augmentation system for an aircraft is presented.

• YAKHAK HOEJI
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• v.44 no.2
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• pp.175-181
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• 2000

Pedunculagin is an ellagitannin purified from Alnus hirsuta var. microphylla, Betulaceae. The effects of pedunculagin on the immune system have been characterized to induce enhancement of NK (natural killer) cell cytotoxicities against tumor cells. The present study investigated whether pedunculagin can enhance macrophage cytotoxicity against P8l5 tumor cells. Macrophage cultured with pedunculagin enhanced cytotoxicity in a dose dependent manner In addition, the same treatments increased NO production, which plays important roles in the immune system. liken together these results demonstrate that pedunculagin significantly enhances cytolytic activities of macrophage.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1619-1625
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• 2017

Civil global navigation satellite system (GNSS) does not meet user performance requirements for specific PNT (Positioning, Navigation, and Time) applications. Therefore, various differential systems are used to augment GNSS for improving positioning accuracy and integrity. The MTSAT satellite augmentation system (MSAS) is the Japanese satellite based augmentation system. This paper is for analyzing the characteristics of Japanese MSAS in Korean peninsula. First of all, it was done for analyzing not only DGNSS navigation signal but also the navigation parameter through simulation and experimental tests. As a result of data analyses, the sufficient navigation satellites to determine 3-D position based on DGNSS are simultaneously available at MSAS monitering station and the southern region of Korean peninsula. It was verified that the carrier to noise signals are stable to maintain the reliable 3-D position and that the level of 2m (2drms) accuracy is very similar to the ordinary worldwide DGNSS as well.

• Journal of Software Engineering Society
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• v.29 no.1
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• pp.13-21
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• 2020

As CNN model is applied to various domains such as image classification and object detection, the performance of CNN model which is used to safety critical system like autonomous vehicles should be reliable. To evaluate that CNN model can sustain the performance in various environments, we developed an image data augmentation apparatus which generates images that is changed background. If an image which contains object is entered into the apparatus, it extracts an object image from the entered image and generate s composed images by synthesizing the object image with collected background images. A s a method to evaluate a CNN model, the apparatus generate s new test images from original test images, and we evaluate the CNN model by the new test image. As a case study, we generated new test images from Pascal VOC2007 and evaluated a YOLOv3 model with the new images. As a result, it was detected that mAP of new test images is almost 0.11 lower than mAP of the original test images.

• Solar Energy
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• v.15 no.3
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• pp.127-140
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• 1995

This experimental study was carried out to examine the heat transfer characteristics of a 2-dimensional impinging air jet on a flat plate with a set of square rods. The objectives of the study were to investigate the flow and heat transfer characteristics caused by the square rods. Experiment was carried out first without using the rods to establish the baseline heat transfer performance. Then, rods of different widths and clearances were installed to cause the turbulence on the fluid flow. When rods are installed in front of the plate, the acceleration of the flow and the turbulence generation due to the rods and reattachment of the flow seem to contribute to the observed heat transfer augmentation and the heat transfer augmentation increases as the clearance decreases. With wider individual rod the heat transfer coefficient is higher, which is due to the increased acceleration and development of the eddies just before the rods.