Enhanced SBAS Integration Method Using Combination of Multiple SBAS Corrections

Yun, Ho,Kim, Do-Yoon,Jeon, Sang-Hoon,Park, Bynng-Woon,Kee, Chang-Don The Korean Society for Aeronautical and Space Scie 2009 International Journal of Aeronautical and Space Sc Vol.10 No.1

In this parer, we propose a new way of improving DGNSS service using combination of multiple SBAS information. Because SBAS uses Geostationary Earth Orbit (GEO) satellites, it has very large coverage but it can be unavailable in urban canyon because of visibility problem. R. Chen solved this problem by creating Virtual Reference Stations (VRS) using the SBAS signal [1]. VRS converts SBAS signal to RTCM signals corresponding its location, and broadcast the converted RTCM signals over the wireless internet. This method can solve the visibility problem cost effectively. Furthermore it can solve DGNSS coverage problem by creating just a transmitter instead of a reference station. Developing above method, this paper proposes the methods that integrate two or more SEAS signals into one RTCM signal and broadcast it. In Korea, MSAS signal is available even though it is not officially certified for Korean users. As a Korean own SBAS-like system, there is the internet-based KWTB (Korean WADGPS Test Bed) which we developed and released at ION GNSS 2006. As a result, virtually two different SBAS corrections are available in Korea. In this paper, we propose the integration methods for these two independent SBAS corrections and present the test results using the actual measurements from the two systems. We present the detailed algorithm for these two methods and analyze the features and performances of them. To verify the proposed methods, we conduct the experiment using the logged SBAS corrections from the two systems and the RINEX data logged at Dokdo monitoring station in Korea. The preliminary test results showed the improved performance compared to the results from two independent systems, which shows the potential of our proposed methods. In the future, the newly developed SBASs will be available and the places which can access the multiple SBAS signals will increase. At that time, the integration or combination methods of two or more SBASs will become more important. Our proposed methods can be one of the useful solutions for that. As an additional research, we need to extend this research to the system level integration such as the concept of the decentralized W ADGPS.

RAIM algorithm considering simultaneous multiple ramp failures

Yun, Ho,Han, Deokhwa,Kee, Changdon,Lee, Jiyun,Heo, Moon Beom Emerald Group Publishing Limited 2015 Aircraft engineering and aerospace technology Vol.87 No.4

<P><B>Purpose</B></P> <P> – The purpose of this paper is to develop and analyze a new multiple hypothesis receiver autonomous integrity monitoring (RAIM) algorithm, which can handle simultaneous multiple ramp failures. </P> <P><B>Design/methodology/approach</B></P> <P> – The proposed algorithm uses measurement residuals and satellite observation matrices of several consecutive epochs for failure detection and exclusion. It detects failures by monitoring the error vector rather than a projection of the error vector. The algorithm assumes that magnitude of range errors can vary with time, while the conventional sequential multiple hypothesis RAIM algorithm assumes that range errors are constant biases. </P> <P><B>Findings</B></P> <P> – The algorithm can detect any instance of multiple failures, including failures that cannot be detected by the conventional RAIM algorithm. It can detect multiple failures with magnitudes of several tens of meters, even though the algorithm must solve an ill-conditioned problem. And it can also deal with ramp failures which cannot be detected by conventional sequential multiple hypothesis RAIM algorithm. The detection capability of the proposed algorithm is not dependent on satellite geometry or types of errors. </P> <P><B>Practical implications</B></P> <P> – Implications for the development of the RAIM algorithm for aviation users are included. In particular, it can be a candidate for a future standard architecture in multiple constellations, multiple frequency and satellite-based augmentation system users. </P> <P><B>Originality/value</B></P> <P> – A new multiple hypothesis RAIM algorithm with a relative RAIM concept is proposed. Also presented is a detailed explanation of the algorithms, including rigorous mathematical expressions, and an analysis of differences in detection capability between the conventional multiple hypothesis RAIM algorithm and proposed algorithm.</P>

Multiple-hypothesis RAIM algorithm with an RRAIM concept

Yun, Ho,Kee, Changdon Emerald Group Publishing Limited 2013 Aircraft engineering and aerospace technology Vol.86 No.1

<B>Purpose</B> - This paper aims to develop and analyse a new multiple-hypothesis receiver autonomous integrity monitoring (RAIM) algorithm. The proposed algorithm can handle simultaneous multiple failures as well as a single failure. <B>Design/methodology/approach</B> - The proposed algorithm uses measurement residuals and satellite observation matrices of several consecutive epochs for failure detection and exclusion. It detects failures by monitoring the error vector itself instead of monitoring the projection of the error vector. The algorithm reduces the minimum detectable bias via the relative receiver autonomous integrity monitoring (RRAIM) scheme. <B>Findings</B> - The algorithm is able to detect any instance of multiple failures, including failures that are not detected by the conventional RAIM algorithm. It is able to detect multiple failures with magnitudes of several tens of meters, although the algorithm has to solve an ill-conditioning problem. The detection capability of the proposed algorithm is not dependent on satellite geometry. <B>Research limitations/implications</B> - The algorithm assumes that the error vectors in three consecutive epochs have biases of similar magnitude. As a result, although the algorithm detects occurrences of drifting error, it cannot identify which measurement(s) has the critical error. <B>Practical implications</B> - The paper includes implications for the development of the RAIM algorithm for aviation users. Especially, it can be a candidate for future standard architecture in multiple constellations, multiple frequency satellite-based augmentation system (SBAS) users. <B>Originality/value</B> - The paper proposes a new multiple-hypothesis RAIM algorithm with an RRAIM concept. A detailed explanation of the algorithms, including rigorous mathematical expressions, is presented. The paper also includes an analysis of differences in detection capability between conventional algorithm and the proposed algorithm depending on satellite geometry.

Korean Wide Area Differential Global Positioning System Development Status and Preliminary Test Results

Yun, Ho,Kee, Chang-Don,Kim, Do-Yoon The Korean Society for Aeronautical and Space Scie 2011 International Journal of Aeronautical and Space Sc Vol.12 No.3

This paper is focused on dynamic modeling and control system design as well as vision based collision avoidance for multi-rotor unmanned aerial vehicles (UAVs). Multi-rotor UAVs are defined as rotary-winged UAVs with multiple rotors. These multi-rotor UAVs can be utilized in various military situations such as surveillance and reconnaissance. They can also be used for obtaining visual information from steep terrains or disaster sites. In this paper, a quad-rotor model is introduced as well as its control system, which is designed based on a proportional-integral-derivative controller and vision-based collision avoidance control system. Additionally, in order for a UAV to navigate safely in areas such as buildings and offices with a number of obstacles, there must be a collision avoidance algorithm installed in the UAV's hardware, which should include the detection of obstacles, avoidance maneuvering, etc. In this paper, the optical flow method, one of the vision-based collision avoidance techniques, is introduced, and multi-rotor UAV's collision avoidance simulations are described in various virtual environments in order to demonstrate its avoidance performance.

A Preliminary Study of Korean Dual-Frequency SBAS

Yun, Ho,Han, Deokhwa,Kee, Changdon The Institute of Positioning 2014 Journal of Positioning, Navigation, and Timing Vol.3 No.1

A Satellite Based Augmentation System (SBAS) is a representative differential GNSS system, which is used for the navigation performance improvement of Global Navigation Satellite System (GNSS) users. SBAS has been developed focusing on the securement of user integrity so that it can be used for the navigation in aviation fields. Accordingly, the development of SBAS has been completed, and it has been actively used in the United States, Europe, and Japan. As the new satellite of Global Positioning System (GPS) recently started to broadcast new civil signals (L5 frequency), the methods for improving user navigation performance in SBAS using this signal have also been studied. In Korea, to keep pace with these circumstances, full-scale SBAS development is expected to start in 2014, and studies on dual-frequency SBAS using L1/L5 frequencies will also be performed. In this study, before the full-scale development of dual-frequency SBAS in Korea, a simulation was performed to predict the performance and analyze the expected effects.

Application & evaluation of IFN-r assay as one of the control program for bovine tuberculosis in Korea

Yunho JANG(Yunho JANG),Tae-woon KIM(Tae-woon KIM),Min Kyu Jeong(Min Kyu Jeong),Yu sin Ok(Yu sin Ok),So yoon Ryoo(So yoon Ryoo),Bang-Hun HYUN(Bang-Hun HYUN),Jae Myung KIM(Jae Myung KIM) 한국예방수의학회 2018 한국예방수의학회 학술대회자료집 Vol.2018 No.-

Development of generalized pustular psoriasis-like eruptions and alopecia areata after biologic therapy in a psoriasis patient

( Yunho Lee ),( Hyeon Jeong Park ),( Junghwa Yang ),( Jung Yup Kim ),( Sunmin Yim ),( Jae Yun Lim ),( Young Jun Choi ),( Jae-hui Nam ),( Ga-young Lee ),( Won-serk Kim ) 대한피부과학회 2018 대한피부과학회 학술발표대회집 Vol.70 No.1

Psoriasis is an immune mediated chronic skin disease that afflicts the patient physically and emotionally. Currently there are many targeted drugs including tumor necrosis factor (TNF) inhibitors, T-cell inhibitors and interleukin (IL)-12/IL-23 inhibitors as effective substitutes for conventional systemic treatments. Although these drugs was proved to be relatively safe, various side effects have been reported. A 46-year-old female had a long-standing history of psoriasis that was inadequately controlled by phototherapy, systemic and topical treatment. Adalimumab (Humira^®) was applied 5 times during two months. One week after fifth injection of adalimumab, her psoriatic lesions were aggravated and numerous scattered erythematous pustules were observed on whole body. Adalimumab was applied 4 times more, but there was no improvement, so she had received ustekinumab (Stelara^®). Two weeks after administarion of ustekimumab, the patient presented with 3 alopecic patches on scalp. Trichoscopy of the affected area showed vellus hair and yellow dot. The patient continued to be treated with ustekinumab (Stelara^®) and applied a topical 0.05% clobetasol-17-propionate (Dermovate^® solution) for alopecia areata treatment, then she experienced improvement of psoriatic lesions and hair regrowth. We report this patient as a case of rare side effects following treatment with biologic agents.

Analysis of N-nitrosamines and other Nitro(so) compounds in Water by High-Performance Liquid Chromatography with Post-column UV Photolysis / Griess Reaction

Yunho Lee(이윤호),Minju Lee(이민주),Urs von Gunten 환경독성보건학회 2013 한국독성학회 심포지움 및 학술발표회 Vol.2013 No.10

Ultrasound Imaging of the Trunk Muscles in Acute Stroke Patients and Relations With Balance Scales

Yunho Kim,Jeeyoung Kim,Heesung Nam,Hyun Dong Kim,Mi Ja Eom,Sang Hoon Jung,Nami Han 대한재활의학회 2020 Annals of Rehabilitation Medicine Vol.44 No.4

Objective To examine the correlation between ultrasonographic trunk muscle parameters and balance scales in mild acute stroke patients. Methods A total of 55 stroke patients with hemiparesis and motor power grade ≥4 in the manual motor test were included. The Scale for the Assessment and Rating of Ataxia (SARA), Berg Balance Scale (BBS), Timed Up and Go Test (TUG), and Trunk Control Test (TCT) were used to evaluate patient balance function. Ultrasonographic parameters were measured on both non-paretic and paretic sides of the rectus abdominis, external oblique, internal oblique, transversus abdominis, and erector spinae muscles. Resting thickness and contraction thickness were measured in all muscles, and contractility and contractility ratio were calculated based on measured thicknesses. The differences between paretic and non-paretic muscle parameters, and the correlation between ultrasonographic parameters and balance scales were analyzed. Stroke patients were divided into two groups according to their fall risk. Ultrasonographic measurements between the two groups were compared. Results All muscles’ contraction thickness and contractility were significantly different between paretic and non-paretic sides (p<0.001). Contractility ratios of all trunk muscles showed a significant correlation with SARA, BBS, TUG, and TCT (p<0.05). Contractility ratios of all muscles were significantly different between high- and low-risk fall groups (p<0.05). Conclusion The contractility ratio in stroke patients reflects their balance disturbance and fall risk and it may serve as a new parameter for ultrasound imaging of trunk muscles.

Remedying Racial Profiling under the Fourteenth Amendment by Analogizing Batson v. Kentucky and State v. Soto

Yunho Yeom 한국형사법무정책연구원 2020 International Journal of Criminal Justice Vol.2 No.1