• Applied Biological Chemistry
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• v.48 no.2
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• pp.115-119
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• 2005

The catalytic hydrolysis reactivities of dinuclear nickel (II) complex, ${\mu}-aquapentaaqua[{\mu}-3,6-bis(6'-methyl-2'-pyridyl)pyridazine]chlorodinickel\;(II)$ trichloride trihydrate (APNT) for bis(p-nitrophenyl) phosphate (BNPP) as a DNA model compound were investigated. The dissociation constants of APNT were $pKa_1=7.9$ and $pKa_2=9.6$, respectively. The hydrolysis rate constant of BNPP compound by APNT was showed the rate enhancement of about 370,000 times in the case of none catalyst at pH 7.0 and $50^{\circ}C$. Based on the findings, we proposed the catalytic cycle for the hydrolysis of BNPP by APNT complex. The metal ions of dinuclear nickel (II) complex significantly enhance the transfer rate of phosphoryl group in the catalytic process and the water molecules as nucleophile and proton transfer agent act in different steps.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.3
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• pp.28-34
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• 2012

The recent transition to Performance Based Navigation in aviation enhances the accuracy of aircraft position, safety and efficiency in air traffic operations by using satellite-based navigation system such as GNSS. However, intentional interferences with GNSS signal as well as ones coming from natural phenomena such as solar storm increase. GNSS have very low power and therefore their signals are more susceptible to interferences than ground-based navigation signals. This paper introduces requirements of alternative positioning, navigation and timing(APNT) system and relevant technologies when the GNSS signals are not valid.

• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.37-44
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• 2016

Republic of Korea has established its performance-based navigation (PBN) implementation plan in 2010 for ensuring a smooth transition to PBN operations and relevant new flight procedures are being developed in accordance with the roadmap. Various Navigation aids (NAVAIDs) like global navigation satellite systems (GNSS), distance measuring equipment (DME), VHF omnidirectional range (VOR), inertial navigation system (INS) are used to support PBN procedures. Among them, GNSS would play a central role in PBN implementation. However, vulnerability of satellite navigation signals to artificial and natural interferences has been discovered and various alternative positioning, navigation and timing (APNT) technologies are under development in many countries. In this paper, we study whether continuous PBN operations can be achievable without GNSS signals. As a result, it shows that some of the domestic airports require the construction of APNT in the approach area.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.4
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• pp.173-180
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• 2016

This paper presents a method to suppress multipath induced by pulses using supervised learning. In modern electronics, pulses have been used for various purposes such as communication or distance measurements. Like other signals, pulses also suffer from multipath. When a pulse and a multipath are overlapped, the original pulse shape is distorted. The distorted pulse could result in communication failures or distance measurement errors. However, a large number of samples available from a pulse can be used to effectively reject multipath by using a supervised learning method. This paper introduces how a supervised learning method can be applied to Distance Measuring Equipment. Simulation results show that multipath induced distance measuring error can be suppressed by 10 ~ 45 percent depending on the allowed pulse shape variation allowed in a standard.

• 한국항공운항학회:학술대회논문집
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• 2015.11a
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• pp.78-82
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• 2015

우리나라는 성능기반항행(PBN)으로 전환하기 위한 단계적 PBN 이행계획을 2010년에 수립하고 로드맵에 따른 새로운 비행절차를 개발 중에 있다. PBN 비행절차에는 GNSS, DME, INS 등의 항법시스템이 활용되는 것으로 되어있다. 그 중에서 GNSS를 이용한 PBN 업무제공이 중심을 이루고 있는 실정이다. 그러나 위성항법신호의 인위적, 자연적 간섭에 의한 취약성이 발견됨에 따라 세계 각국은 다양한 대안항법 기술을 연구하고 있다. 본 논문에서는 GNSS 신호가 가용하지 않을 경우 기존의 항행시스템으로 지속적인 PBN 운항이 가능한지를 검토해 보고, 필요시 활용할 수 있는 적절한 대안항법을 논의하고자 한다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.3
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• pp.35-41
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• 2015

Multilateration(MLAT) is commonly used in civil and military surveillance applications to accurately locate an aircraft, vehicle or stationary emitter. MLAT calculates the TDOA of signals by transmitted aircraft and determines the aircraft's location. With more than four receivers it is possible to estimate the 3D position of the aircraft by calculating the intersection of the resulting hyperbolas and the system integrity. In this study, our objectives are to apply MLAT technique to Jeju terminal control area and to propose a MLAT receiver network to properly estimate the positions of aircraft approaching this area. Based on computer simulations, we determine locations of ground receivers in Jeju terminal control area, calculate estimated position errors of the aircraft with respect to the selected receiver networks, and find the best receiver network with the least position error.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.2
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• pp.113-120
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• 2021

The Distance Measuring Equipment (DME) is a ground-based aircraft navigation system and is considered as an infrastructure that ensures resilient aircraft navigation capability during the event of a Global Navigation Satellite System (GNSS) outage. The main problem of DME as a GNSS back up is a poor positioning accuracy that often reaches over 100 m. In this paper, a novel approach of applying deep reinforcement learning to a DME pulse design is introduced to improve the DME distance measuring accuracy. This method is designed to develop multipath-resistant DME pulses that comply with current DME specifications. In the research, a Markov Decision Process (MDP) for DME pulse design is set using pulse shape requirements and a timing error. Based on the designed MDP, we created an Environment called PulseEnv, which allows the agent representing a DME pulse shape to explore continuous space using the Soft Actor Critical (SAC) reinforcement learning algorithm.