김미현 Mi-hyun Kim , 나범철 Beom-cheol Na , 김기태 Ki-tae Kim , 전상현 Sang-hyun Jeon

DOI: JANT Vol.28(No.6) 767-774, 2024

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Recent advancements in drone and aerial weapon systems have emphasized the importance of precise navigation systems. Such weapons require sophisticated navigation technology to accurately reach targets. However, accumulated errors in the Inertial Measurement Unit (IMU), a critical sensor in precise navigation systems, significantly impact targeting accuracy. To address this issue, this study introduces a novel Unscented Extended Kalman Filter (UEKF) algorithm, which combines the prediction step of the Unscented Kalman Filter (UKF) with the update step of the Extended Kalman Filter (EKF). Our experiments, conducted across various environments including EKF, UKF, and a no-filter baseline, demonstrate that the UEKF algorithm improves accuracy by up to 62% and achieves up to 21% faster real-time processing performance compared to traditional filter algorithms. This performance enhancement is expected to greatly advance the efficacy of various navigation weapon systems and lay the foundation for developing next-generation precision navigation devices.

손민혁 Minhyuk Son , 박건환 Geonhwan Park , 박소라 So-ra Park , 정환호 Hwanho Jeong , 이병석 Byungseok Lee , 김정자 Jungja Kim , 송영재 Youngjae Song

DOI: JANT Vol.28(No.6) 775-783, 2024

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KASS (Korea augmentation satellite system) is a satellite navigation-based calibration system that complies with international standards for aviation users. As aviation users who utilize it should continuously ensure accuracy, integrity, availability, and continuity, the KASS service provider should continuously verify and ensure their quality. The PDAT(performance degradation monitoring tool) supports system state and service performance monitoring, operation management, and training/testing, while the PDAT verifies the suitability of KASS signals and messages in quasi-real time, calls the user performance tool using the reference station and user receiver, and compares the support information for issuing the air notification. In this study, we introduced the configuration of the PDAT and KASS message, and derived the method and results of verifying the detailed functions of the tool.

진성근 Seong-keun Jin , 정한균 Han-gyun Jung , 김주영 Ju-young Kim , 곽재민 Jae-min Kwak

DOI: JANT Vol.28(No.6) 784-789, 2024

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In the recent automotive market, autonomous driving technology has been rapidly advancing. Beyond autonomous passenger vehicles, the development of autonomous driving for commercial vehicles and related autonomous transportation technologies is also progressing actively. Commercial vehicles exhibit unique dynamic characteristics compared to passenger vehicles due to various factors such as the type of cargo, packaging units, and weight. Therefore, road infrastructure support is essential to ensure safe autonomous operation. This paper proposes a safety evaluation methodology for the V2X communication system implemented in the “Saemangeum Autonomous Transportation Commercial Vehicle Demonstration Infrastructure”, established to support autonomous transportation with commercial vehicles. The results derived from the field tests were visualized, confirming the ability to quickly identify and address the root causes of failures. Additionally, delay measurements based on time synchronization demonstrated a precision level of ±0.1 ms even in asynchronous environments, validating the reliability and applicability of the proposed evaluation method.

김유진 Eugene Kim , 정다님 Danim Jung , 김의호 Euiho Kim , 이진실 Jinsil Lee , 고요한 Yohan Ko , 김수경 Su-kyung Kim

DOI: JANT Vol.28(No.6) 790-802, 2024

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To ensure the integrity of satellite navigation systems, various satellite signal monitoring mechanisms are required, among which Signal Quality Monitoring (SQM) is responsible for detecting Evil Waveforms (EWF) caused by satellite hardware faults. Existing research on SQM techniques and methodologies for defining the Threat Space (TS) of EWF has primarily been developed with augmentation systems in mind. However, the next-generation Regional Navigation Satellite System (N-RNSS) will work without augmentation systems. This means that new TS definitions and SQM techniques must be created that are specifically for N-RNSS signals. This paper summarizes prior research on signal distortion models and TS definition methodologies, and proposes development plans for SQM techniques suitable for N-RNSS signals based on the assumptions and conditions of N-RNSS monitoring stations.

왕수현 Soo-hyun Wang

DOI: JANT Vol.28(No.6) 803-808, 2024

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Maritime vessel detection is critical in various fields such as maritime safety, security, and environmental protection. However, vessel detection becomes increasingly challenging in low-visibility conditions, such as nighttime or adverse weather. To address this issue, infrared (IR) cameras are employed. Nevertheless, IR cameras face limitations due to low resolution and limited color information, making the detection of small vessels particularly difficult. This study proposes a multi-scale attention (MSA) technique based on convolutional neural network (CNN) feature maps to accurately detect vessels of various sizes. By leveraging the multi-scale feature maps of YOLOv8, MSA improves the detection of small vessels while maintaining real-time detection performance. Experimental results demonstrate that the proposed model enhances the detection precision for small and medium-sized vessels in IR-based detection, thereby maximizing real-time detection performance in maritime environments.

김수현 Soohyun Kim , 최지효 Jihyo Choi , 임상호 Sangho Lim , 손인혜 Inhye Son , 신동조 Dongcho Shin

DOI: JANT Vol.28(No.6) 809-818, 2024

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Autofocus techniques improve image quality by compensating for phase errors in SAR (synthetic aperture radar) imagery, with PGA (phase gradient autofocus) being the most widely used. Phase errors that occur during SAR imagery formation process degrade quality of SAR imagery. However, conventional PGA techniques may not estimate the phase error properly in the presence of adjacent strong signals in the azimuth direction, such as man-made structures, and may actually degrade the image quality. In this paper, we propose a method to estimate and compensate for the phase error by selecting analytically meaningful signals during target selection for phase error estimation. The performance of the improved PGA method is quantitatively compared and validated based on the conventional PGA method using real airborne SAR data, which results in decreasing number of iteration from 5 to 3, decreasing residual error from 1658.3 mrad. to 45.79 mrad., 87% improvement in -3 dB resolution and 19.53 dB and 18.61 dB improvement in ISLR, PSLR, respectively.

이승준 Seungjun Lee , 김태호 Taeho Kim , 김웅이 Woongyi Kim , 장호상 Hosang Chang , 구성관 Sungkwan Ku

DOI: JANT Vol.28(No.6) 819-826, 2024

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Due to the concentration of the population in metropolitan areas, congestion in ground transportation networks in urban areas is worsening. Urban air mobility(UAM), a three-dimensional transportation method, is emerging as an alternative and is being presented as a solution. Vertiports are one of the most important infrastructures for operating UAM, and in order for UAM aircraft to take off and land safely, analysis of the environment surrounding the vertiport, such as obstacles and weather, is essential. In this study, we analyzed the criteria for environmental analysis related to obstacles and weather around vertiports, and conducted an empirical analysis targeting candidate sites for vertiports in the Jeju island based on these criteria. We expect that this study will be serve as a reference guideline for reviewing the selection of candidate sites for vertiports in the future.

박상도 Sang-do Park , 김진영 Jin-young Kim , 김영륜 Young-ryun Kim , 정동원 Dongwon Jung , 전향식 Hyang-sig Jun

DOI: JANT Vol.28(No.6) 827-836, 2024

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According to the K-UAM Concept of Operations, K-UAM navigation is based on PBN. PBN is further divided into RNAV and RNP, which are distinguished by the presence or absence of onboard performance monitoring capabilities. Given that urban air mobility operates along predefined corridors within complex urban environments, RNP-based navigation performance monitoring is essential to ensure safe operations. In this study, integrity monitoring algorithms deemed suitable were applied based on the environmental factors considered at each operational phase. A simulator was developed using realistic data, and the results confirmed that the proposed navigation requirements were met during the cruising, approach, and landing phases.

정성훈 Seong-hoon Jeong

DOI: JANT Vol.28(No.6) 837-843, 2024

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Marine satellite data exhibits complex spatiotemporal characteristics, necessitating the development of standardized metadata for systematic management and interoperability. This study proposes a framework for designing and generating metadata in JSON, XML, RDF, and CSV formats by integrating international standards (ISO 19115, ISO/IEC 11179) and domestic standards. The research process includes defining metadata elements, schema design, generation, and validation, utilizing tools such as JSONLint, XML Editor Online, EasyRDF, and Online CSV Editor to ensure data quality and interoperability. Additionally, a standard integration logic and a format conversion engine were developed. Through case studies, the study provides a detailed methodology for metadata creation and validation, confirming improved data usability and seamless data exchange between systems. The results demonstrate that metadata standardization enhances data consistency, reliability, accessibility, and improves the efficiency of data-driven decision-making. Future research should focus on incorporating new data formats and advancing additional standardization efforts to further strengthen the scalability and consistency of metadata management.

박정환 Jung-hwan Park , 류재영 Jae-young Ryu , 김태영 Tae Young Kim , 이석환 Seokhwan Lee , 박민균 Minkyun Park , 이학태 Hak-tae Lee

DOI: JANT Vol.28(No.6) 844-854, 2024

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Generally, commercial transport aircraft are quipped with automatic dependent surveillance - broadcast (ADS-B) out that broadcast its position and other state information at a regular interval via transponder. This system can supplement the ground radar surveillance system and also can be used to mitigate the airborne collision risk. In this paper, the process of formally registering an ADS-B out/transponder integrated equipment for a small drone is outlined. In addition, the reception range are measured and conflict detection and resolution test are performed with a small drone equipped with the ADS-B out and ground-based ADS-B receiver stations. The study experimentally confirmed that it is possible to control a small drone similar to the radar separation between commercial aircraft traffic.