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조경학,이병영,권명흠,김석철 한국대기환경학회 2019 한국대기환경학회지 Vol.35 No.2
A deep neural network (DNN) model of multi-layer perceptron with 3 or 4 hidden layers is developed to predict the air qualities. The DNN model takes the past 3 days of the hourly concentration measurements of the pollutants (CO, SO2, NO2, O3, PM10, PM2.5) and the meteorology data (wind speed, wind direction, air temperature, air humidity), and then predicts the hourly concentration of the pollutants for the next 24 hours. The DNN model was compared against the observations from all nationwide air quality monitoring stations which includes 115 sites in 7 metropolitan cities in South Korea. The index of agreement (IOA) was found to be 0.7~0.8, based upon the 6,505 comparison data sets from January 1, 2017 to September 30, 2017. In the unit of air quality grade, which can be evaluated from the pollutant concentration level, 60%~80% cases of the DNN predictions agree with those of the observations. For the region-wide PM10 grade, the DNN predicts exactly the 75%~85% cases of the observations, which is in about the same accuracy range of the numerical air quality models of the current operative use. Yet, for the region-wide PM2.5 grade, the cases of the accurate predictions of DNN is about twice of those of the numerical model. In the metropolitan Gwangju, for an example, the DNN predicts exactly the 211 next days of the PM2.5 grade, while the numerical model forecasts just 120 days correctly.
항공용 인터콤의 백업 모드 운용을 위한 디지털 방식의 이중화 설계
정성재,조경학,김동혁,이성우,Jeong, Seong-jae,Cho, Kyung-hak,Kim, Dong-hyouk,Lee, Seong-woo 한국항행학회 2022 韓國航行學會論文誌 Vol.26 No.5
The Inter Communication System for avionics is in charge of processing all voice signals that internal calls between Pilot and Co-pilot, internal calls between Pilots and Crews, external calls through communication equipment such as Ultra/Very High Frequency Receiver/Transmitter(U/VHF RT), audio signal monitoring for navigation and mission equipment such as VHF Omnidirectional Range/Instrument Landing System(VOR/ILS), Tactical Air Navigation(TACAN), audio signal output for voice recording to Flight Data Recorder(FDR) and Data Transfer System(DTS), and warning/caution audio signal generate about the status and threat of aircraft. Because Inter Communication System for avionics is sensitive to noise in the case of analog audio signals, a redundant design that can protect audio signal from electromagnetic noise inside/outside of aircraft is required for the mission of pilots and crews. In this paper, Normal/Back-up operation mode and redundancy design plan based on digital method for the redundancy of the digital Inter Communication System for avionics and manufacturing, verification results are described.
문기영,김석철,신구용,조경학,윤정임,황규석,길용식 한국풍공학회 2009 한국풍공학회지 Vol.13 No.3
Winds over a complex terrain were analyzed using wind tunnel and several computational fluid dynamics (CFD) models. A mountain area adjacent to a shoreline was chosen in a Southern Korea Peninsula for study. Two different CFD models were used for simulating flows: one is an FVM code with Virtual Boundary Method(VBM) using LES for sub-grid turbulence, and the other is a commercial package implemented with 4 different RANS (Reynolds Averaged Navier-Stokes Equations) turbulence models. The CFD simulations were compared with wind tunnel data at several locations where wind speeds were greatly enhanced or reduced due to the surrounding topographic features. The agreement between the CFD simulations and the wind tunnel experiments were good, the correlation coefficients ranging 0.890 ~ 0.965. The FVM code was excellent of which correlation coefficient was 0.965. 자연지형에 의한 기류 변화를 CFD 모델과 풍동실험을 통하여 비교 연구하였다. 해안에 인접한 남부 산악지형을 대상으로 풍동실험과 몇 종류의 CFD 모델 시뮬레이션을 수행하였다. 사용한 CFD 모델은 2 가지로, 하나는 LES 난류모델을 사용하는 가상경계기법을 활용한 유한체적법(Finite Volume Method, FVM) 코드와 또 하나는 4 가지 RANS 난류모델이 선택사양으로 제공되는 상업용 CFD 모델이다. 지형에 의해 풍속이 증가되는 지점과 감소되는 지점에서 수직풍속분포를 직접 비교하고 상관도를 구하였다. CFD 모델과 풍동실험과의 상관도()는 0.890 ~ 0.965로 매우 높게 나타났으며, CFD 모델 중 VBM LES CFD 모델은 상관도 0.965로 나타나 풍동실험을 가장 잘 모사하는 것으로 분석되었다.
김만달(M. D. Kim),홍성욱(S. W. Hong),현종훈(J. H. Hyun),조경학,김동국(D. K. Kim),이승준(S. J. Lee),K. H. Choi 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
Missile Pod installing missiles and many components can be operated automatically for Hybrid Weapon System. this study has found out a dynamic characteristic about the changed structure of the missile pod. through this paper, first, Modeling and simulation was showed that can be adoptable the change structure for the missile pod through vibration and shock analysis by NASTRAN. Vibration test for this missile pod performs and verifies of the performance of this missile pod