• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.2
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• pp.81-88
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• 2023

SHM (Structural Health Monitoring) technique for monitoring aircraft structural health and damage, EHM (Engine Health Monitoring) for monitoring aircraft engine performance, and APM (Application Performance Management) is used for each function. APMS (Airplane Performance Monitoring System) is a program that comprehensively applies these techniques to identify the difference between the performance manual provided by the manufacturer and the actual fuel mileage of the aircraft and reflect it in the flight plan. The main purpose of using APMS is to understand the performance of each aircraft, to plan and execute flights in an optimal way, and consequently to reduce fuel consumption. First, it is to check the fuel efficiency trend of each aircraft, check the correlation between the maintenance work performed and the fuel mileage, find the cause of the fuel mileage increase/decrease, and take appropriate measures in response. Second, it is to find the cause of fuel mileage degradation in detail by checking the trends by engine performance and fuselage drag effect. Third, the APMS is to be used in making maintenance work decisions. Through APMS, aircraft with below average fuel mileage are identified, the cause of fuel mileage degradation is identified, and appropriate corrective actions are determined. Fourth, APMS data is used to analyze the economic analysis of equipment installation investment. The cost can be easily calculated as the equipment installation cost, but the benefit is fuel efficiency improvement, and the only way to check this is the manufacturer's theory. Therefore, verifying the effect after installation and verifying the economic analysis is to secure the appropriateness of the investment. Through this, proper investment in fuel efficiency improvement equipment will be made, and fuel efficiency will be improved.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.441-447
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• 2022

In this paper, we propose a FLL-assisted-PLL based time synchronization algorithm for telemetry systems where frequency and phase errors exist in time synchronization pulse. The telemetry system may analyze the flight state by acquiring the state information in the distributed system. Therefor, in order to collect each state information without errors, precise time synchronization between the master and the slave is required. At this time, the master's time pulse have frequency and phase changes that can be caused by external and internal factors, so a method to maintain precision time synchronization is essential to provide telemetry data continuously. We propose the FLL-assisted-PLL based algorithm that is capable of high-speed synchronization and has high time synchronization accuracy. The proposed algorithm is verified through python simulation, and the VHDL Logic has been implemented in FPGA to check the performance according to the frequency errors and phase errors.

• Mycobiology
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• v.51 no.5
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• pp.360-371
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• 2023

Hispidin is an important styrylpyrone produced by Sanghuangporus sanghuang. To analyze hispidin biosynthesis in S. sanghuang, the transcriptomes of hispidin-producing and non-producing S. sanghuang were determined by Illumina sequencing. Five PKSs were identified using genome annotation. Comparative analysis with the reference transcriptome showed that two PKSs (ShPKS3 and ShPKS4) had low expression levels in four types of media. The gene expression pattern of only ShPKS1 was consistent with the yield variation of hispidin. The combined analyses of gene expression with qPCR and hispidin detection by liquid chromatography-mass spectrometry coupled with ion-trap and time-of-flight technologies (LCMS-IT-TOF) showed that ShPKS1 was involved in hispidin biosynthesis in S. sanghuang. ShPKS1 is a partially reducing PKS gene with extra AMP and ACP domains before the KS domain. The domain architecture of ShPKS1 was AMP-ACP-KS-AT-DH-KR-ACP-ACP. Phylogenetic analysis shows that ShPKS1 and other PKS genes from Hymenochaetaceae form a unique monophyletic clade closely related to the clade containing Agaricales hispidin synthase. Taken together, our data indicate that ShPKS1 is a novel PKS of S. sanghuang involved in hispidin biosynthesis.

• Journal of The Korean Astronomical Society
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• v.56 no.2
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• pp.293-299
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• 2023

The Wide-Angle Polarimetric Camera (PolCam) is installed on the Korea's lunar orbiter, Danuri, which launched on August 5, 2022. The mission objectives of PolCam are to construct photometric maps at a wavelength of 336 nm and polarization maps at 461 and 748 nm, with a phase angle range of 0°-135° and a spatial resolution of less than 100 m. PolCam is an imager using the push-broom method and has two cameras, Cam 1 and Cam 2, with a viewing angle of 45° to the right and left of the spacecraft's direction of orbit. We conducted performance tests in a laboratory setting before installing PolCam's flight model on the spacecraft. We analyzed the CCD's dark current, flat-field frame, spot size, and light flux. The dark current was obtained during thermal / vacuum test with various temperatures and the flat-field frame data was also obtained with an integrating sphere and tungsten light bulb. We describe the calibration method and results in this study.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.888-896
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• 2023

When an aircraft is landing, it is expected that the aircraft will follow a specified approach procedure and then land at the airport. However, depending on the airport situation, neighbouring aircraft or the instructions of the air traffic controller, there can be a deviation from the specified approach. Detecting aircraft approach patterns is necessary for traffic flow and flight safety, and this paper suggests clustering techniques to identify aircraft patterns in the approach segment. The Gaussian Mixture Model (GMM), one of the machine learning techniques, is used to cluster the trajectories of aircraft, and ADS-B data from aircraft landing at the Gimhae airport in 2019 are used. The aircraft trajectories are clustered on the plane, and a total of 86 approach trajectory patterns are extracted using the centroid value of each cluster. Considering the correlation between the approach procedure pattern and overshoots, the distribution of overshoots is calculated.

• International Journal of Computer Science & Network Security
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• v.24 no.1
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• pp.226-234
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• 2024

The frequent handover problem and playing ping-pong effects in 5G (5th Generation) ultra-dense networking cannot be effectively resolved by the conventional handover decision methods, which rely on the handover thresholds and measurement reports. For instance, millimetre-wave LANs, broadband remote association techniques, and 5G/6G organizations are instances of group of people yet to come frameworks that request greater security, lower idleness, and dependable principles and correspondence limit. One of the critical parts of 5G and 6G innovation is believed to be successful blockage the board. With further developed help quality, it empowers administrator to run many systems administration recreations on a solitary association. To guarantee load adjusting, forestall network cut disappointment, and give substitute cuts in case of blockage or cut frustration, a modern pursuing choices framework to deal with showing up network information is require. Our goal is to balance the strain on BSs while optimizing the value of the information that is transferred from satellites to BSs. Nevertheless, due to their irregular flight characteristic, some satellites frequently cannot establish a connection with Base Stations (BSs), which further complicates the joint satellite-BS connection and channel allocation. SF redistribution techniques based on Deep Reinforcement Learning (DRL) have been devised, taking into account the randomness of the data received by the terminal. In order to predict the best capacity improvements in the wireless instruments of 5G and 6G IoT networks, a hybrid algorithm for deep learning is being used in this study. To control the level of congestion within a 5G/6G network, the suggested approach is put into effect to a training set. With 0.933 accuracy and 0.067 miss rate, the suggested method produced encouraging results.

• Journal of Advanced Navigation Technology
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• v.28 no.2
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• pp.163-171
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• 2024

In the existing air traffic management (ATM) system, various types of safety alert features are provided based on trajectory data to ensure the safety of aircraft operations, along with aircraft position and detailed flight information. The urban air traffic management (UATM) system for urban air mobility (UAM) should also provide safety alert features to ensure the safety of UAM operations. Considering the operational environment of UAM, it is necessary that the safety alert features provided at least match or exceed those available in the existing ATM system. This study aims to present the safety alert features of the new UATM system that differ from those provided by the existing ATM system before introduction and commercialization of UAM. The study was conducted focusing on the safety alert features that should be provided in the event of a deviation from the UAM's path, and the establishment of the safety alert features was carried out in two parts: approach path monitor (APM), which is applied during the approach phase, and route adherence monitoring (RAM), which is applied during the cruise phase.

• Anatomy and Cell Biology
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• v.57 no.1
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• pp.119-128
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• 2024

Glucocorticoids play a physiologic role in the adult male reproductive functions, modulating gonadal steroid synthesis and spermatogenesis, through the glucocorticoid receptor (GR). The expression of GR has been described in several key testicular cell types, including somatic cells and early germ cell populations. Nothing is known on GR in human spermatozoa. Herein, we explored the GR expression and its possible role in normal and testicular varicocele semen samples from volunteer donors. After semen parameter evaluation by macro- and microscopic analysis, samples were centrifuged; then spermatozoa and culture media were recovered for further investigations. By western blotting and immunofluorescence analyses we evidenced for the first time in spermatozoa the presence of GR-D3 isoform which was reduced in sperm from varicocele patients. By treating sperm with the synthetic glucocorticoid dexamethasone (DEXA), we found that survival, motility, capacitation, and acrosome reaction were increased in both healthy and varicocele samples. GR involvement in mediating DEXA effects, was confirmed by using the GR inhibitor mifepristone (M2F). Worthy, we also discovered that sperm secretes different cortisol amounts depending on its physio-pathological status, suggesting a defence mechanism to escape the immune system attach in the female genital tract thus maintaining the immune-privilege as in the testis. Collectively, our data suggests a role for glucocorticoids in determining semen quality and function, as well as in participating on sperm immune defensive mechanisms. The novelty of this study may be beneficial and needs to take into account in artificial insemination/drug discovery aimed to enhancing sperm quality.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.393-399
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• 2024

The digital map computer for advanced air vehicles (AAV) must be high-performance, lightweight, portable, and modular. It should receive data on terrain, weather, and obstacles from external modules to display digital maps accurately. This necessitates robust communication capabilities with external devices via an Ethernet interface and the ability to output digital map visuals clearly through an high-defintion multimedia Interface (HDMI) or digital visual interface (DVI) interface. This paper presents the design of both hardware and software architecture that fulfills these critical requirements for an AAV digital map system. Additionally, it establishes the minimum specifications needed and verifies the suitability of the designed digital map computer through rigorous performance measurements and testing. By ensuring these standards, the digital map computer can reliably support the complex navigational needs of AAV, enhancing operational efficiency and safety.

• Economic and Environmental Geology
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• v.41 no.2
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• pp.211-217
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• 2008

The gravity anomalies that observed by ground and shipborne survey and calculated from GRACE satellite are combined by using spherical cap harmonic analysis (SCHA). In this study, ground gravity data from Korea Institute of Geoscience and Mineral Resource(KIGAM) and shipborne gravity data from National Ocean Research Institute(NORI) and Korea Ocean Research and Development institute(KORDI) were used. L-2 level GRACE Gravity Model (GGM02C) was also used for satellite gravity anomaly. The ground and shipborne surveyed data were combined and gridded using Krigging method with 0.05 degree interval and GRACE data were also gridded using the same method with 0.05 degree to harmonize with the resolution of SCHA that has coefficient up to 80. Generalized Minimal Residual(GMRES) inversion method was implemented for calculating the coefficients of SCHA using the gridded ground and satellite gravity anomalies that had 0 km and 50 km altitude, respectively. The results of inversion method showed good correlation of 0.950 and 0.995 with original ground and satellite data. The gravity anomaly using SCHA satisfies Laplace's equation, therefore, using these SCHA coefficients, gravity anomaly can be calculated at any altitude. In this study, gravity anomaly was calculated from 10 km to 60 km altitude and each altitude, very stable results were shown. The ground and shipborne gravity data that have higher resolution and satellite data in long wavelength are harmonized well with SCHA coefficients and successfully applied in South Korea area. If more continuous survey and muti-altitude surveyed data like airborne data available, more precise gravity anomaly can be acquired using SCHA method.