Sensitivity Evaluation of Physics and Initial Condition of WRF for Ultra Low Altitude Wind Prediction
권재일 Jaeil Kwon , 김기영 Ki-young Kim , 구성관 Sungkwan Ku , 홍석민 Seokmin Hong
23(6) 487-494, 2019
권재일 Jaeil Kwon , 김기영 Ki-young Kim , 구성관 Sungkwan Ku , 홍석민 Seokmin Hong
DOI: JANT Vol.23(No.6) 487-494, 2019
Recently, interest in and use of drones is increasing. In this study, to provide accurate wind prediction at ultra low altitudes of 150 meters or below, the sensitivity of the physical process parameterization and initial conditions was assessed to select the optimal physical process and initial conditions. For this purpose, GFS and LDAPS data were used as initial and boundary conditions, and 7 experiments were constructed using a combination of PBL schemes such as YSU, RUC, ACM2, and LSM such as Noah, RUC, and Pleim. The experiment conducted for 1 month in April 2018. As a result, the RUC-YSU physical process combination using the GFS initial data showed the best performance. This study is meaningful in establishing an optimal modeling method for ultra low altitude wind prediction through experiments using different initial conditions and combination of physical processes.
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Performance Comparison and Test of Fixed FOD Automatic Detection System and Moving FOD Automatic Detection System
김성희 Sung-hee Kim , 홍재범 Jae-beom Hong , 박광근 Kwang-gun Park , 최인규 In-kyu Choi , 홍교영 Gyo-young Hong
23(6) 495-500, 2019
김성희 Sung-hee Kim , 홍재범 Jae-beom Hong , 박광근 Kwang-gun Park , 최인규 In-kyu Choi , 홍교영 Gyo-young Hong
DOI: JANT Vol.23(No.6) 495-500, 2019
Foreign object debris (FOD) is a generic term for various metals and non-metal foreign object and materials with potential hazards to aircraft operations. Since the method of manual FOD detection and collection in the aircraft moving area is very low in efficiency and economic efficiency, it is essential to develop to FOD automatic detection system suitable for domestic environment. This paper is the result of the performance comparison test results of the two systems for the combined operation of each optimal detection time and 95% accuracy above 100 m for complex operation using the fixed FOD automatic detection system and the mobile FOD system using EO/IR camera and radar at Taean Airfield Hanseo University. It is expected that FOD can be performed unattended through continuous R & D.
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Domestic Application Plan of Fatigue Risk Management System by Air Traffic Controller
이영종 Young-jong Lee
23(6) 501-506, 2019
이영종 Young-jong Lee
DOI: JANT Vol.23(No.6) 501-506, 2019
This paper presents a prescriptive alternative for establishing a FRMS suitable for us based on scientific data ahead of the introduction and implementation of the FRMS for air traffic controllers in order to meet the International Civil Aviation Organization (ICAO) international standards. I would like to present. Therefore, we confirmed the operation of each air traffic control agency against the current domestic operating standards, and compared and reviewed the operation methods and standards of air traffic control agencies in each country. The controller in Korea defines 10 hours of working hours per day, 8 hours of minimum breaks, and 40 hours per week. Currently, in the case of air traffic control agencies, the daytime and the appropriate working hours are used in the daytime, but in the nighttime, the average time exceeds 5.9 hours. In the case of 40 hours a week, they work an average of 15.7 hours overtime. By adjusting the nighttime work time, this work can be solved by diversifying the form of the worker's input method according to the personal schedule rather than the two-day (day / night) method, as well as the appropriate nighttime time distribution by supplementing the personnel.
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Frequency Sharing with FSS Earth Stations for CBRS Services
강영흥 Young-heung Kang
23(6) 507-514, 2019
강영흥 Young-heung Kang
DOI: JANT Vol.23(No.6) 507-514, 2019
Federal communications commissions (FCC) has announced the first set of rules for 3.5 GHz (3,550 - 3,700 MHz) band used Navy radar and fixed satellite service (FSS) earth stations as primary service to sharing for citizen broadband radio service (CBRS) enable development of relatively low powered network technologies like small cells. Since CBRS sharing technique based on the 3-tiered spectrum access system (SAS) is able to protect the higher tiered users from harmful interference from lower tiered users, it has been considered actively to be introduced in Korea. However, 3.5 GHz band had been already allocated to the 5G services in Korea, the sharing studies have been carried out for 3,700 - 5,000 MHz, As the result, the 3.8 GHz (3,800 - 3,900 MHz) band used for only FSS system is able to be sharing, and an introduction of CBRS has been proposed in Korea by analyzing the interference to the FSS earth stations.
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Performance Analysis of GNSS Based Precise Positioning User System According to Driving Condition
이정훈 Jung-hoon Lee , 이상우 Sangwoo Lee , 안종선 Jongsun Ahn , 임성혁 Sunghyuck Im , 천세범 Sebum Chun , 허문범 Moon-beom Heo
23(6) 515-521, 2019
이정훈 Jung-hoon Lee , 이상우 Sangwoo Lee , 안종선 Jongsun Ahn , 임성혁 Sunghyuck Im , 천세범 Sebum Chun , 허문범 Moon-beom Heo
DOI: JANT Vol.23(No.6) 515-521, 2019
The C-ITS requires the lane level positioning of the vehicle in the land transportation environment, and it is most effective to utilize the global navigation satellite system. In the precision positioning system based on satellite navigation, the evaluation of dynamic environment of lane level positioning performance should be accompanied and the evaluation system configuration should be preceded. In addition, performance analysis must be performed according to various environments that change according to traffic or road conditions in a dynamic environment. In this paper, we describe with the performance of traffic and road environment through the evaluation system of lane positioning precision positioning user system based on satellite navigation system. The numerical performance evaluation was carried out based on the data collected by carrying out the actual driving. The performance evaluation by the actual driving trajectory and driving image comparison was performed to derive and analyse evaluation results of positioning performance according to driving condition
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Analysis of Radio Distortion in Navigational Aid using Drone
이영길 Young-gil Lee , 이현성 Hyeon-sung Lee
23(6) 522-525, 2019
이영길 Young-gil Lee , 이현성 Hyeon-sung Lee
DOI: JANT Vol.23(No.6) 522-525, 2019
To overcome the limitation of ground inspection for Navigational Aid, Korea Airport Corporation (KAC) developed a drone system for Navigational Aid inspection. This drone system has the advantage that they can inspect the air radio signal at the perspective of user (aircraft). Since drones have more free flight paths and easier control of flight speeds compared to aircrafts, drones can check sections of suspected airborne radio wave distortions at desired paths and speeds. Recently, with the acceleration of the development around the airport, there is a concern about the deterioration of the quality of radio signal of Navigational Aid. In order to analyze radio distortion of Navigational Aid, a radio wave environmental survey was conducted using drones. When the signal received by each flight path of the drone was measured, the origin of the reflected wave was identified by analyzing the section in which the radio signal was distorted.
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ANN based Indoor Localization Method using the Movement Pattern of Indoor User
서재희 Jae-hee Seo , 천세범 Sebum Chun , 허문범 Moon-beom Heo
23(6) 526-534, 2019
서재희 Jae-hee Seo , 천세범 Sebum Chun , 허문범 Moon-beom Heo
DOI: JANT Vol.23(No.6) 526-534, 2019
Localization methods using radio signals should obtain range measurements from three or more anchors. However, a typical building consists of narrow, long hallways and corners, making it difficult to secure more than three light of sight anchors. The result is a multi-modal solution that makes it difficult to estimate the user's location. In order to overcome this problem, this paper proposes a method for estimating the location using artificial neural networks. Using the artificial neural network, even if a multi-modal solution occurs, the position can be estimated by acquiring user movement pattern information based on accumulated range measurements. The method does not require any additional equipment or sensors, and only anchor-based range measurements can estimate the user's location. In order to verify the proposed method, location estimation tests were performed in situations where the multi-modal solution occurred by installing an insufficient number of anchors in a building. As a result, it was confirmed that the location can be estimated even when the number of anchors is insufficient.
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Precise Orbit Estimation of GPS using GIPSY-OASIS
하지현 Jihyun Ha , 천세범 Sebum Chun , 박관동 Kwan-dong Park
23(6) 535-541, 2019
하지현 Jihyun Ha , 천세범 Sebum Chun , 박관동 Kwan-dong Park
DOI: JANT Vol.23(No.6) 535-541, 2019
In this paper, scripts for estimating the reference orbits of navigation satellites were developed and their performance was analyzed as a preliminary study for the development of the Korean GPS precise orbit determination technology. The JPL Flinn AC's data processing strategy was applied and Linux-based scripts were developed using GIPSY-OASIS. For the analysis of the accuracy of the estimated reference orbit, the precise orbit provided by the international GNSS data center was used as the truth. As a result, estimated satellite coordinates showed almost exactly same patterns and trends with the reference precise orbits, and their differences are in the range of ±2 cm. The average error between the two orbits was less than 1 cm in the 3D direction, while the standard deviation was also at 1 cm. From these, we found that the developed scripts have excellent performance in precise orbit determination
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Distributed UORA Scheme for Autonomous Train Communication in Congested Environment
안우진 Woojin Ahn , 김용호 Ronny Yongho Kim
23(6) 542-547, 2019
안우진 Woojin Ahn , 김용호 Ronny Yongho Kim
DOI: JANT Vol.23(No.6) 542-547, 2019
Autonomous train is investigated to increase the capacity of railroad, and the reliability of wireless communication plays a critical role in terms of decreasing the inter-train distance. In this paper, we propose a transmission scheme for autonomous train communication in highly congested environment. The proposed scheme, namely distributed uplink orthogonal frequency division multiple access (OFDMA) random access (UORA), applies the triggered uplink access (TUA) and the UORA, introduced in the sixth generation WLAN standard, IEEE 802.11ax, for communication devices on vehicle and platform in a distributed manner. The simulation results show that the proposed scheme efficiently improves the packet transmission success rate in highly congested channel conditions compared to the conventional enhanced distributed channel access (EDCA) transmission scheme.
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A V2V Transmission Scheme for Safety Message Dissemination in Platooning
안우진 Woojin Ahn , 홍한슬 Hanseul Hong , 김용호 Ronny Yongho Kim
23(6) 548-553, 2019
안우진 Woojin Ahn , 홍한슬 Hanseul Hong , 김용호 Ronny Yongho Kim
DOI: JANT Vol.23(No.6) 548-553, 2019
Along with advanced vehicle to vehicle (V2V) communication technologies, platooning is regarded as one of the most promising form of autonomous driving solutions in order to increase road capacity. In this paper, we propose a novel V2V transmission scheme for safety message dissemination in platooning. The proposed scheme enhances the efficiency of channel access and multi-vehicle orthogonal frequency division multiple access (OFDMA) transmission by taking advantage of triggered uplink access technique and null data packet feedback report protocol introduced in the sixth generation WLAN standard, IEEE 802.11ax. The simulation results prove that the proposed scheme outperforms the conventional IEEE 802.11 transmission scheme throughout all measured vehicle density range.
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Input Signal Selection Circuits Development of Electronic Cards for Thermal Degradation in Nuclear Power Plant
김종호 Jong-ho Kim , 최규식 Gyu-shik Che
23(6) 554-560, 2019
김종호 Jong-ho Kim , 최규식 Gyu-shik Che
DOI: JANT Vol.23(No.6) 554-560, 2019
Excore Nuclear Flux Monitoring System in Nuclear Power Plant monitors continuous reactor power up to maximum 200%. The monitoring method, however, has to be different depending on the reactor power level. Because the logarithmic pulse signals must be counted and processed exactly due to large uncertainty if their levels are low, on the other hand, they must be processed through statistical methodolgies if theirs are high to get exact monitoring values, in point of thermal degradation view. Therefore, we developed thermal degradation input signal selection circuit to transfer low level reactor power monitoring circuit to high level reactor power circuit at rated value in this paper. We proved their validities through testing them using real data used in nuclear power plant and analyzed their results. And, These methods will be used to measure the neutron level of excore nuclear flux monitoring system in nuclear power plant.
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Prediction of Short and Long-term PV Power Generation in Specific Regions using Actual Converter Output Data
하은규 Eun-gyu Ha , 김태오 Tae-oh Kim , 김창복 Chang-bok Kim
23(6) 561-569, 2019
하은규 Eun-gyu Ha , 김태오 Tae-oh Kim , 김창복 Chang-bok Kim
DOI: JANT Vol.23(No.6) 561-569, 2019
Solar photovoltaic can provide electrical energy with only radiation, and its use is expanding rapidly as a new energy source. This study predicts the short and long-term PV power generation using actual converter output data of photovoltaic system. The prediction algorithm uses multiple linear regression, support vector machine (SVM), and deep learning such as deep neural network (DNN) and long short-term memory (LSTM). In addition, three models are used according to the input and output structure of the weather element. Long-term forecasts are made monthly, seasonally and annually, and short-term forecasts are made for 7 days. As a result, the deep learning network is better in prediction accuracy than multiple linear regression and SVM. In addition, LSTM, which is a better model for time series prediction than DNN, is somewhat superior in terms of prediction accuracy. The experiment results according to the input and output structure appear Model 2 has less error than Model 1, and Model 3 has less error than Model 2.
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Dispersion-Managed Link with Different Numbers of Fiber Spans and Asymmetric Distribution of RDPS
홍성화 Sung-hwa Hong , 이성렬 Seong-real Lee
23(6) 570-576, 2019
홍성화 Sung-hwa Hong , 이성렬 Seong-real Lee
DOI: JANT Vol.23(No.6) 570-576, 2019
The configuration of dispersion-managed optical link with optical phase conjugator, which is placed at the non-midway of total transmission length, is proposed for implementing of the flexible optical network. The optical phase conjugator is located between the former half transmission section and the latter half transmission section, which are consisted of 6 fiber spans and 14 fiber spans respectively, and the averaged RDPS of each half transmission section are inconsistence. And, the artificial distribution of each fiber span’s RDPS, which are gradually increased/decreased as the span numbers are increased, is adopted to compensate for the distorted wavelength division multiplexed channels. From the simulation results, it is confirmed that the compensation in dispersion-managed link configured by a special distribution pattern among 16 proposed patterns, in which the RDPS of each fiber spans are gradually decreased/increased in the former/latter half section with the small deviation, is suitable to compensate for the distorted wavelength division multiplexed channels.
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Stability Conditions for Positive Time-Varying Discrete Interval System with Unstructured Uncertainty
한형석 Hyung-seok Han
23(6) 577-583, 2019
한형석 Hyung-seok Han
DOI: JANT Vol.23(No.6) 577-583, 2019
A dynamic system is called positive if any trajectory of the system starting from non-negative initial states remains forever non-negative for non-negative controls. In this paper, we consider the new stability condition for the positive time-varying linear discrete interval systems with time-varying delay and unstructured uncertainty. The delay time is considered as time-varying within certain interval having minimum and maximum values and the system is subjected to nonlinear unstructured uncertainty which only gives information on uncertainty magnitude. The proposed stability condition is an improvement of the previous results which can be applied only to time-invariant systems or had no consideration of uncertainty, and they can be expressed in the form of a very simple inequality. The stability conditions are derived using the Lyapunov stability theory and have many advantages over previous results using the upper solution bound of the Lyapunov equation. Through numerical example, the proposed stability conditions are proven to be effective and can include the existing results.
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Link Budget Analysis of Communication System for Reliable WBAN
노재성 Jae-sung Roh
23(6) 584-588, 2019
노재성 Jae-sung Roh
DOI: JANT Vol.23(No.6) 584-588, 2019
Wireless body area network (WBAN) is a networking technology that enables early detection of abnormal health conditions, real-time medical monitoring, and telemedicine support systems. The internet of things (IoT) for healthcare, which has become an issue recently, is one of the most promising areas for improving the quality of human life. It must meet the high QoS requirements of the medical communication system like any other communication system. Therefore, the bit error rate (BER) threshold was chosen to accommodate the QoS requirements of the WBAN communication system. In this paper, we calculated BER performance of WBAN channel using IR-UWB PPM modulation and analyzed link budget and system margin of WBAN according to various system parameters.
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A Primary Channel Selection Scheme for Wideband WLAN V2X Communication
홍한슬 Hanseul Hong , 김용호 Ronny Yongho Kim , 안우진 Woojin Ahn
23(6) 589-596, 2019
홍한슬 Hanseul Hong , 김용호 Ronny Yongho Kim , 안우진 Woojin Ahn
DOI: JANT Vol.23(No.6) 589-596, 2019
With the proliferation of intelligent transportation system (ITS) with dedicated short-range communication (DSRC) deployment, there are various applications requiring different throughput and reliability performance. To meet the enhanced throughput requirements in newly generated applications, IEEE 802.11bd is proposed to standardize for support of enhanced throughput and latency, preserving the fairness with previously deployed WLAN V2X devices. One of the main features of IEEE 802.11 bd is 20 MHz transmission to support the high data rate. In this paper, the primary channel selection method is proposed to guarantee the fairness with frame transmissions with 10 MHz bandwith including communications in WLAN V2X devices deployed with IEEE 802.11p. Simulation shows that the proposed channel access method for 20 MHz transmission with primary selection preserves the fairness without the change of channel access method in wide-band transmission.
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Development for Estimation Improvement Model of Wind Velocity using Deep Neural Network
구성관 Sungkwan Ku , 홍석민 Seokmin Hong , 김기영 Ki-young Kim , 권재일 Jaeil Kwon
23(6) 597-604, 2019
구성관 Sungkwan Ku , 홍석민 Seokmin Hong , 김기영 Ki-young Kim , 권재일 Jaeil Kwon
DOI: JANT Vol.23(No.6) 597-604, 2019
Artificial neural networks are algorithms that simulate learning through interaction and experience in neurons in the brain and that are a method that can be used to produce accurate results through learning that reflects the characteristics of data. In this study, a model using deep neural network was presented to improve the predicted wind speed values in the meteorological dynamic model. The wind speed prediction improvement model using the deep neural network presented in the study constructed a model to recalibrate the predicted values of the meteorological dynamics model and carried out the verification and testing process and Separate data confirm that the accuracy of the predictions can be increased. In order to improve the prediction of wind speed, an in-depth neural network was established using the predicted values of general weather data such as time, temperature, air pressure, humidity, atmospheric conditions, and wind speed. Some of the data in the entire data were divided into data for checking the adequacy of the model, and the separate accuracy was checked rather than being used for model building and learning to confirm the suitability of the methods presented in the study.
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