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Because of the rapid increase of mobile traffic, flexible broadband supportive unmanned aerial vehicle (UAV)‐based 6G mobile networks using free space optical (FSO) links have been recently proposed. Considering the advancements made in UAVs, big data processing, and artificial intelligence precision control technologies, the formation of an additional wireless network based on UAV aerial platforms to assist the existing fixed base stations of the mobile radio access network is considered a highly viable option in the near future. In this paper, a combined time bound optimization scheme is proposed that can adaptively satisfy the control and communication time constraints as well as the processing time constraints in FSO‐based 6G UAV aerial networks. The proposed scheme controls the relation between the number of data flows, input data rate, number of worker nodes considering the time bounds, and the errors that occur during communication and data processing. The simulation results show that the proposed scheme is very effective in satisfying the time constraints for UAV control and radio access network services, even when errors in communication and data processing may occur.

Novel analytical platforms for high-throughput determination of lipid turnover in vivo have been developed based on partial metabolic 2H2O labeling. The performance on lipid kinetics measurement of our methods was validated in three different liquid chromatography–mass spectrometry (LC-MS) setups: MS-only, untargeted MS/MS, and targeted MS/MS. The MS-only scheme consisted of multiple LC-MS runs for quantification of lipid mass isotopomers and an extra LC-MS/MS run for lipid identification. The untargeted MS/MS format utilized multiple data-dependent LC-MS/MS runs for both quantification of lipid mass isotopomers and lipid identification. An in-house software was also developed to streamline the data processing from peak area quantification of mass isotopomers to exponential curve fitting for extracting the turnover rate constant. With HeLa cells cultured in 5% 2H2O media for 48 h, we could deduce the species-level turnover rates of 108 and 94 lipids in the MS-only and untargeted MS/MS schemes, respectivel...

This study describes the theoretical performance of a successive interference cancellation (IC) technique as an electronic counter countermeasure and verifies its feasibility through experiments. In a radio navigation system using direct sequence/code division multiple access, strong pseudorandom signals can be used as interference sources for unauthorised users when regional radio navigation needs to be denied in a specific area, while authorised users can use both the strong signal and the global navigation satellite system (GNSS) ranging signal for navigation through the IC method. To determine the feasibility of this selective jamming concept, this study investigated its theoretical performance and compared the results with experimental ones. The experimental results show that a maximum jamming-to-signal ratio performance of 57 dB or higher can be achieved, which is similar to the theoretical estimation.

Limited studies on multi-omics have been conducted to comprehensively investigate the molecular mechanism underlying the developmental neurotoxicity of perfluorooctanesulfonic acid (PFOS). In this study, the locomotor behavior of zebrafish larvae was assessed under the exposure to 0.1–20 μM PFOS based on its reported neurobehavioral effect. After the number of zebrafish larvae was optimized for proteomics and metabolomics studies, three kinds of omics (i.e., transcriptomics, proteomics, and metabolomics) were carried out with zebrafish larvae exposed to 0.1, 1, 5, and 10 μM PFOS. More importantly, a data-driven integration of multi-omics was performed to elucidate the toxicity mechanism involved in developmental neurotoxicity. In a concentration-dependent manner, exposure to PFOS provoked hyperactivity and hypoactivity under light and dark conditions, respectively. Individual omics revealed that PFOS exposure caused perturbations in the pathways of neurological function, oxidative stress, and energy metabolism. Integrated omics implied that there were decisive pathways for axonal deformation, neuroinflammatory stimulation, and dysregulation of calcium ion signaling, which are more clearly specified for neurotoxicity. Overall, our findings broaden the molecular understanding of the developmental neurotoxicity of PFOS, for which multi-omics and integrated omics analyses are efficient for discovering the significant molecular pathways related to developmental neurotoxicity in zebrafish.

2011년 국제회계기준 도입으로 기업은 이자와 배당의 수취 및 지급의 현금흐름표상 분류에 대한 선택권을 갖게 되었다. 이에 본 연구는 이자와 배당의 수취 및 지급을 그 경제적 실질에 따라 각각 투자활동과 재무활동으로 분류한 기업을 대상으로 그 분류 유인을 살펴본다. 또한 K-GAAP에서는 이자와 배당의 수취 및 지급을 영업활동으로 분류하였으므로 기업이 이자와 배당의 수취 및 지급을 투자활동과 재무활동으로 분류한다면, 이는 현금흐름의 분류를 변경한 것이라고 할 수 있다. 따라서 본 연구는 기업이 이자와 배당의 수취 및 지급의 분류를 변경하는 경우 이러한 분류변경으로 인해 활동별 현금흐름의 정보효과에 변동이 있는지를 연구한다. 실증분석 결과, 이자와 배당지급액의 합계가 이자와 배당수취액의 합계보다 크면 기업은 이들 항목을 그 성격에 따라 투자활동과 재무활동으로 분류하는 경향이 있다. 또한 이자와 배당수입 및 이자지급을 K-GAAP에 따라 영업활동으로 분류하는 경우 보고될 투자활동 현금흐름이 소속 산업 평균보다 낮으면 이들 항목을 그 성격에 따라 분류하는 것으로 나타난다. 아울러 기업의 현금흐름을 예측하는 애널리스트가 존재하는 경우 이자와 배당의 수취 및 지급을 그 경제적 실질에 따라 분류하는 것으로 나타난다. 이자와 배당수입 및 이자지급을 그 성격에 따라 분류하는 경우 영업활동 현금흐름의 가치관련성이 증가한다. 이는 이자와 배당의 수취 및 지급을 영업활동에서 제외하여 각각 투자활동과 재무활동으로 표시함에 따라 영업활동 현금흐름의 질이 증가하여 그 가치관련성이 증가함을 시사한다.

Global navigation satellite systems (GNSS) is operating widely in civil and military area. GNSS signals, however, can be easily interfered because its signal is vulnerable to jamming. Thus, a sort of backup or alternative system is needed in order that the navigation performance is assured to a certain degree in case of GNSS jamming. In order to suggest a series of backup or alternative system of regional navigation, in this paper, we introduced a high altitude long endurance unmanned aerial vehicle (HALE UAV) with pseudolites using inverted GPS and transceiver system. We simulated the positioning error of the regional navigation system using HALE UAV with inverted GPS or transceivers concepts. We estimated the position error of HALE UAV calculate user position errors based on the position error of HALE UAV and general pseudorange error.

Since Google launched the Android N in 2016, more than 30 brand new Android devices are providing user-domain with GNSS raw measurements, which are pseudorange, carrier phase and doppler observables. Before the Android N there was no other way to improve the position accuracy of the smart phone or tablet than A-GPS or DGPS-CP, which were only available at server-side or under a constraint of satellite visibility. Even though there is not yet any GNSS augmentation functionality implemented to feed the correction to the chipset, the access to the raw measurements allow users to improve the position accuracy of the devices and to applies them to various areas as desired. There are typical ways to correct the device pseudorange-based position such as DGNSS (Differential GNSS), PPP (Precise Point Positioning), SBAS (Satellite Based Augmentation System) and so on. In the case of DGNSS, DGNSS reference stations broadcast the PRC (Pseudo Range Correction) whose service area is 150km to 200km from each station, thus the user should include a function of selecting the reference station according to the user’s location. PPP is another augmentation solution which provides a global precise positioning service that uses detailed physical models and corrections, and precise GNSS orbit and clock products. One of the many advantages of PPP is that the PPP solutions of GNSS orbit and clock products are global. Currently, the IGS (International GNSS Service) provides users with the RTS products which consist of GNSS satellite orbit and clock corrections to the broadcast ephemeris in real time, whose data rate in IGS RTS (Real Time Service) product stream is about 2,000bps. SBAS is also a powerful enhancement to augment GPS by broadcasting augmentation messages including differential corrections and integrity information with a very low data rate of 250bps from a GEO satellite. Unlike DGNSS, all the users in the SBAS service area receive the same correction and information, so the user app does not need any model for selecting the reference station. Moreover, the data bandwidth is only 250 bps, which is about 10% of the PPP service, thus the users does not need to feel burdened by the cost of mobile data communication even though current GNSS module in Android device should receive the SBAS message on the internet, not on the L1 signal. Despite of the simplicity at the user side and the low data rate for the correction message, current SBAS system cannot fully utilize the multi-constellation effect of the Android devices. All the current SBAS systems except of the SDCM of Russia provide GPS-only augmentation messages, thus when Android smart devices supporting multi-constellations(GPS, GLONASS, Galileo, etc.) cannot utilize the advantages(i.e. improving the accuracy) of multi-constellations when applying the current SBAS message. To complement this disadvantage, we propose the L1 SFMC (Single-Frequency, Multi-Constellation) SBAS in this paper. The L1 SFMC SBAS method and its message protocols were the method suggested at ION GNSS+ 2017 to improve the performance of the L1 single frequency GNSS by containing all the information for the multi-constellation GNSS in the modified SBAS message format. We propose to remove the fast corrections and to assign additional time slots for providing the long-term corrections of GLONASS and other constellations. To include our suggested L1 SFMC SBAS in the suggested message format, we generated the long-term corrections using the precise orbit and clock products from the IGS Data Center. Also, we generated the ionospheric corrections for all the constellation using IGP(Ionospheric Grid Point) vertical delay estimates which has already been included in SBAS Message Type 26 and IONEX data. We carried out some experiments to confirm the effect of our suggested L1 SFMC SBAS corrections on Android smart device at Seoul, Korea. As a result of applying the L1 SFMC SBAS corrections to Android GNSS raw measurements on Samsung Galaxy S8 with 250bps, the mean values have been reduced from 2.02m(horizontal) and 9.49m(vertical) to 0.36m and 0.49m, and the RMS errors have been reduced from 5.19m(horizontal) and 10.56m(vertical) to 1.30m and 2.06m.

The Ground-based Radio Navigation System (GRNS) is an alternative/backup navigation system based on time synchronized pseudolites. It has been studied for some years due to the potential vulnerability issue of satellite navigation systems (e.g., GPS or Galileo). In the framework of our study, a periodic pulsed sequence was used instead of the randomized pulse sequence recommended as the RTCM (radio technical commission for maritime services) SC (special committee)-104 pseudolite signal, as a randomized pulse sequence with a long dwell time is not suitable for applications requiring high dynamics. This paper introduces a mathematical model of the post-correlation output in a navigation sensor, showing that the aliasing caused by the additional frequency term of a periodic pulsed signal leads to a false lock (i.e., Doppler frequency bias) during the signal acquisition process or in the carrier tracking loop of the navigation sensor. We suggest algorithms to resolve the frequency false lock issue in this paper, relying on the use of a multi-correlator. A flight test with an unmanned helicopter was conducted to verify the implemented navigation sensor. The results of this analysis show that there were no false locks during the flight test and that outliers stem from bad dilution of precision (DOP) or fluctuations in the received signal quality.

A door checker holds a car door at several opening angles and limits the maximum door opening, so that the door does not bump against to passengers. Recently, the performance of door checker becomes more important as the feeling of door opening and closing effects on the quality of a car. However, some of door checkers make squealing noise when they are used for ages, which causes consumer's complaints as well as decreasing commercial value of the product. In this study, after various experiments for the noise, we concluded that the major reasons of the noise are acceleration of wearing and loss of lubricant due to impurities in working parts. Therefore, we developed a new mechanism of door checker which can resolve the major reasons of the noise. The developed mechanism is effective to prevent inflow of impurities and loss of lubricant by locating working parts in the case. We also proved that the developed mechanism does not make any noise after the test of 50,000 times of operations.

In the case of satellite navigation positioning, the shielding of satellite signals is determined by the environment of the region at which a user is located, and the navigation performance is determined accordingly. The accuracy of user position determination varies depending on the dilution of precision (DOP) which is a measuring index for the geometric characteristics of visible satellites; and if the minimum visible satellites are not secured, position determination is impossible. Currently, the GLObal NAvigation Satellite system (GLONASS) of Russia is used to supplement the navigation performance of the Global Positioning System (GPS) in regions where GPS cannot be used. In addition, the European Satellite Navigation System (Galileo) of the European Union, the Chinese Satellite Navigation System (BeiDou) of China, the Quasi-Zenith Satellite System (QZSS) of Japan, and the Indian Regional Navigation Satellite System (IRNSS) of India are aimed to achieve the full operational capability (FOC) operation of the navigation system. Thus, the number of satellites available for navigation would rapidly increase, particularly in the Asian region; and when integrated navigation is performed, the improvement of navigation performance is expected to be much larger than that in other regions. To secure a stable and prompt position solution, GPSGLONASS integrated navigation is generally performed at present. However, as available satellite navigation systems have been diversified, finding the minimum satellite constellation combination to obtain the best navigation performance has recently become an issue. For this purpose, it is necessary to examine and predict the navigation performance that could be obtained by the addition of the third satellite navigation system in addition to GPS-GLONASS. In this study, the current status of the integrated navigation performance for various satellite constellation combinations was analyzed based on 2014, and the navigation performance in 2020 was predicted based on the FOC plan of the satellite navigation system for each country. For this prediction, the orbital elements and nominal almanac data of satellite navigation systems that can be observed in the Korean Peninsula were organized, and the minimum elevation angle expecting signal shielding was established based on Matlab and the performance was predicted in terms of DOP. In the case of integrated navigation, a time offset determination algorithm needs to be considered in order to estimate the clock error between navigation systems, and it was analyzed using two kinds of methods: a satellite navigation message based estimation method and a receiver based method where a user directly performs estimation. This simulation is expected to be used as an index for the establishment of the minimum satellite constellation for obtaining the best navigation performance.

All the current SBAS systems broadcast the augmentation message based on the L1-only SBAS MOPS (Minimum Operational Performance Standards), which is described in the RTCA DO-229 as an international standard. The L1 SBAS message was originally designed to support multi-GNSS constellations, but all the SBAS systems except for the SDCM of Russia provide GPS-only augmentation message. There are several reasons (i.e. a low data-rate) why most SBAS systems cannot support the multi-constellation GNSS. In order to overcome the limitations of the existing L1-only SBAS MOPS and to improve the performance of the current operating SBAS systems, studies on the L1/L5 DFMC (Dual-Frequency, Multi-Constellation) SBAS are actively ongoing. FAA (Federal Aviation Administration) in United States and the ESA (European Space Agency) have held the SBAS IWG (Interoperability Working Group) and have continued to discuss the development of the L1/L5 DFMC SBAS. However, even if the development of the L1/L5 DFMC SBAS is completed, many users with a L1 single frequency and multi-constellation GNSS receiver, which occupies most of the GNSS receiver market share, cannot use the L1/L5 DFMC SBAS. Therefore, it is necessary to study on a method to improve the performance of the L1-only SBAS. We propose to remove the fast corrections and to assign additional time slots for providing the long-term corrections of GLONASS and other constellations. As we had already proven at the ION ITM 2017, the PRC (Pseudo-Range Correction) in MT (Message Type) 2 to 5 needs not to be broadcast every 6 seconds, and it can be included to the satellite clock correction term in MT 25 after being converted into the unit of second. If the fast correction is not broadcast, half of the time slots are available and enough to send the long-term corrections for other constellations than GPS. And, we generated the long-term corrections for GLONASS satellites using GLONASS satellite precise ephemeris from the IAC (Information and Analysis Center). GLONASS long-term corrections were packed in MT 25 and these additional messages were scheduled in the empty time slots obtained by removing the fast correction. In this paper, we suggested to remove the fast correction and to modify the broadcasting timing and very few parameters of the current L1 SBAS message. We also showed that even this minor modification is working with the live SBAS message and effective to reduce the size of the protection level by supporting the multi-constellation GNSS, which will also contribute to improve the performance of integrity, availability and continuity.

A new LQG based vector tracking algorithm using additional tracking loops for high disturbance environment is presented. The conventional vector tracking algorithm does not estimate errors such as atmospheric delay error and multipath because vector tracking algorithm first estimates the position and estimates the measurements. Therefore, additional tracking loops defined as range domain loop in this paper compensate for these errors to enable continuous signal tracking. In order to evaluate the performance of the proposed algorithm, we compare the LQG based vector tracking algorithm with the EKF and loop filter based vector tracking algorithm and confirm that the LQG based vector tracking algorithm is more robust than EKF based vector tracking algorithm especially in a dynamic user environment. In addition, we confirm that the LQG based vector tracking algorithm with range domain loop can maintain the signal tracking successively in high disturbance environment caused by multiple error sources. Finally, LQG based vector tracking algorithm with range domain loop can be similar results compared to LQG-VTL in no disturbance environment.

For the purpose of improving the accuracy of Wide Area Differential GNSS (WA-DGNSS), estimation performance of ionospheric delay error which has a great impact on GPS error sources should be enhanced. This paper applied multi-constellation GNSS which represents GPS in USA, GLONASS in Russia, and Galileo in Europe to WA-DGNSS algorithm in order to improve performance of ionospheric delay estimation. Furthermore, we conducted simulation to analyze ionospheric delay estimation performance in Korean region by increasing the number of reference stations. Consequently, using multi-constellation GNSS to improve performance of ionospheric delay estimation is more effective than increasing the number of reference stations in spite of similar number of measurements which are in use for estimation. We expect this result can contribute to improvement for ionospheric delay estimation performance of single-frequency SBAS (Satellite Based Augmentation System) user.

Time synchronization system using dual frequency bands is designed and the error sources are analyzed for alternative synchronized-pseudolite navigation system (S-PNS) which aims at military application. To resolve near/far problem, dual frequency band operation is proposed instead of pulsing transmission which degrades level of reception. In dual frequency operation H/W delay should be considered to eliminate errors caused by inter-frequency bias (IFB) difference between the receivers of the pseudolites and users. When time synchronization is performed across the sea, multipath error is occurred severely since the elevation angle between pseudolites is low so total reflection can be happened. To investigate the difference of multipath effects according to location, pseudolites are set up coastal area and land area and performances are compared. The error source related with tropospheric delay is becoming dominant source as the coverage of the PNS is broadening. The tropospheric delay is measured by master pseudolite receiver directly using own pseudorange and slave pseudorange. Flight test is performed near coastal area using S-PNS equipped with developed time synchronization system and test results are also presented.

This paper presents a 144 GHz divide-by-2 injection locked frequency divider (ILFD) with inductive feedback developed in a commercial 90-nm Si RFCMOS technology. It was demonstrated that division-by-2 operation is achieved with input power down to -12 dBm, with measured locking range of 0.96 GHz (144.18 - 145.14 GHz) at input power of -3 dBm. To the authors' best knowledge, this is the highest operation frequency for ILFD based on a 90- nm CMOS technology. From supply voltage of 1.8 V, the circuit draws 5.7 mA including both core and buffer. The fabricated chip occupies 0.54 mm × 0.69 mm including the DC and RF pads.

In this work, a 18 GHz divide-by-4 injection-locked frequency divider(ILFD) based on ring oscillator has been developed in Si RFCMOS technology. The free-running oscillation frequency is from 4.98 to 5.22 GHz and output power is about －30 dBm, consuming 33.4 mW with a 1.5 V supply voltage. At 0 dBm input power, the locking range is 3.5 GHz(17.75~21.25 GHz) and with varactor tuning, the operating range is increased up to 5.25 GHz(16.0~21.25 GHz). The fabricated chip size is including DC and RF pad.

In this work, a divide-by-2 injection locked frequency divider (ILFD) operating in the V-band with a low DC power consumption has been developed in a commercial 0.13-µm Si RFCMOS technology. The bias current path was separated from the injection signal path, which enabled a small supply voltage of 0.5V, leading to a DC power consumption of only 0.31mW. To the authors' best knowledge, this is the lowest power consumption reported for mm-wave ILFDs at the point of writing. All inductors and interconnection lines were designed based on EM (electromagnetic) simulator for precise prediction of circuit performance. With varactor tuning voltage ranged for 0-1.2V, the free-running oscillation frequency varied from 27.43 to 28.06GHz. At 0dBm input power, the frequency divider exhibited a locking range of 5.8GHz from 53 to 58.8GHz without external tuning mechanism. The fabricated circuit size is 0.72mm × 0.62mm including the RF and DC supply pads.

An injection-locked frequency divider (ILFD) with an inductive feedback for enhanced locking range has been developed in a commercial 0.13 μm Si RFCMOS technology and compared with a conventional ILFD. The proposed ILFD showed a significant improvement in the locking range over the conventional ILFD, operating at a frequency range of 43.60-48.95 GHz. The dc power consumption of the ILFD was 0.58 mW with a supply voltage of 1.2 V for the divider core.

A 20–30 GHz divide-by-3 ring-based injection locked frequency divider (ILFD) using NMOS loads for a wide locking range has been developed in a commercial 0.13-μm Si RFCMOS technology.The ILFD shows a locking range up to 7.5 GHz (20.8−28.3 GHz, 30.5%) and operation range of 10 GHz (20.8–30.8 GHz, 38.8%) with DC power consumption of 13 mW and a 1.5 V supply voltage. The fabricated circuit occupies only 0.008 mm2 core area. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:389–841, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25883

In this paper, using the additional relation between tropospheric delay and height variation, we combined multiple carrier phase corrections from multiple reference stations of Network RTK. The Low-order Surface Method (LSM) is used as a base correction interpolation method. The LSM including height difference is also considered and its gradient coefficients are calculated as minimum-norm solutions. Real GPS data from multiple reference station network are collected and Compact RTK and Master-Auxiliary Concept (MAC) corrections are generated. Finally, generated corrections are tested for various correction interpolation methods including proposed algorithm and their performances are compared.

A number of government-sponsored large-scale R&D projects in the telecommunications sector have been carried out in Korea. Among them is the time division exchange (TDX) project that lasted for more than 15 years. The project has two characteristics: the commercialization of government-sponsored R&D and the commercialization of R&D with multiple development cycles. This paper describes these characteristics of the project from various viewpoints: product development strategy, the role of each organization, success factors of each product, the classification of commercial products by commercialization model, and technology transfer strategies encouraging participation of manufacturing firms. We conclude with several recommendations.

Global competitive environment in telecommunications requires that the current R&D project selection process should be changed. This paper argues that quality function deployment(QFD) matrix that has been successfully used for drawing technologies from customer needs can be applied to the selection of telecommunications technologies. It describes the selection process by successive matrix handling. The steps to draw technology priority are detailed. Nominal measures, such as current company rating, competitor's ratings, planned level, improvement ratio, that are used for prioritizing customer needs in QFD matrix, cannot be directly applied to telecommunications. Instead, several new measures are devised to prioritize telecommunications services and to develop competitive benchmarks.

Summary form only given. The technology policies, for instance, R&D programs supported by the government have been playing great roles to develop IT (information and telecommunications) industry and digital economy in Korea. However, in order to be effective, their missions and roles could not be the same as the IT industry grows. Therefore the policies should be carefully designed along with the industrial and technological changes. In this context, this paper analyzes how the roles of national R&D programs of Korea were changed and how accordingly the policy measures of Korea affected the development of IT industry and the infrastructure for the digital economy of Korea.

Nowadays, various research has been done for cubesat, a nano-satellite small and inexpensive compared to general satellites. It is used for educational reasons, cost reduction, and various other missional reasons. Most of the cubesats have been launched for low earth orbit (LEO) where orbit environments such as eclipse and various disturbance torques, such as gravity gradient torque, solar radiation torque, and aerodynamic torque exist. Since cubesats have small moment of inertia (MOI) causing it to be sensitive for disturbance torques existing in the low earth orbit. Therefore, designing attitude control algorithm is important not only for the survival, but also for successful mission. This paper will examine the attitude determination and control system (ADCS) algorithm for cubesat SNUGLITE (Seoul National University GNSS Laboratory satellITE) and show how the proposed algorithm satisfies the ADCS requirements considering the operation scenario. The ADCS is composed of 3-axis MEMs gyroscope sensor, 2-axis coarse photodiode type sun sensors, 3-axis MEMs magnetometer, dual frequency GPS receivers, and 3-axis magnetic torquers. The EKF (Extended Kalman Filter) and LQG (Linear Quadratic Gaussian) controller has been chosen for ADCS algorithm for SNUGLITE. Furthermore, this paper will provide SILS (Software In the Loop System) that simulates the space environment to verify the proposed ADCS algorithm.