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회전 변조 시준기(RMC) 데이터와 영상화 알고리즘 시뮬레이션
신영준(Youngjun Shin),김기현(Geehyun Kim),이계민(Gyemin Lee) 대한전자공학회 2015 대한전자공학회 학술대회 Vol.2015 No.11
Rotating Modulation collimator(RMC) is a remote sensing technique for a radiation source. In this paper, we introduce an RMC system model and simulate RMC modulation profiles. We also derive an image reconstruction algorithm based on maximum likelihood method and demonstrate its performance using MonteCarlo simulation data on the RMC.
LES기반 연소모델과 Helmholtz 방정식을 이용한 LIMOUSINE 버너의 연소불안정 해석
신영준(Youngjun Shin),전상태(Sangtae Jeon),김용모(Yongmo Kim) 한국연소학회 2017 한국연소학회지 Vol.22 No.3
This study has numerically investigated the flame—acoustics interactions in the turbulent partially premixed flame field. In the present approach, in order to analyze the combustion instability, the present approach has employed the LES-based combustion model as well as the Helmholtz solver. Computations are made for the validation case of the partially premixed LIMOUSINE burner. In terms of the FFT data, numerical results are compared with experimental data. Moreover, Helmholtz equation in frequency domain is solved by combining CFD field data including the flight time from a nozzle to the flame zone. Based on numerical results, the detailed discussions are made for the essential features of the combustion instability encountered in the partially premixed burner.
수소첨가 천연가스 희박예혼합 연소에 대한 수치해석 연구
신영준(Youngjun Shin),조은성(Eun-Seong Cho) 한국연소학회 2021 한국연소학회지 Vol.26 No.1
Hydrogen enriched LNG flame is tested to understand hydrogen effect on the flame such as temperature, flame speed, emissions (NOx, CO), and extinction at lean premixed (ф=0.4~0.6) various pressure (p=1~25 bar) conditions using CHEMKIN-Pro with GRI 3.0 detailed chemistry. Hydrogen flame temperature is much higher than that of LNG, which may affect high NOx emission production. The flame speed increases with the addition of H₂, so a design speed change should be considered to prevent flashback at the nozzle. The addition of H₂ reduces CO emissions and increases NOx emissions, but can be overcome with a lower equivalent ratio due to the increased flame stabilization due to the addition of H₂. Extinction stretch rate gradually increases with hydrogen addition which shows that enriched hydrogen LNG premixed flame could be sustainable in high turbulent condition which means more stable than LNG itself flame. Even though in 100% H₂ operating condition, gas turbine operating condition shows similar combustion air and exit flue gas flow rate with LNG which means the compressor and turbine may not need major modification.
신영준(Youngjun Shin),김기현(Geehyun Kim),이계민(Gyemin Lee) 대한전자공학회 2016 전자공학회논문지 Vol.53 No.9
방사능 누출 사고 시 대응이나 핵안보 검증을 위한 핵물질 탐지에 있어서, 방사선을 방출하는 미지의 선원에 대한 위치 정보를 파악하는 것은 중요하다. 그러한 기구 중 하나인 회전 변조 시준기는 미지 선원을 원격 감지하기 위한 장비로서 영상화를 통해 선원의 위치 탐지가 가능하다. 본 논문에서는 Kowash의 연구를 기초로 회전 변조 시준기의 시스템 모델과 그를 영상화하는 알고리즘을 소개한다. 하지만 결과 영상화 이미지는 선원의 방향은 보여줄 수 있으나 선원의 거리를 찾지 못하는 문제점이 있다. 또한 선원의 실제 방향뿐 아니라 180° 대칭방향에서도 선원을 추정하는 모호성 문제를 안고 있다. 본 논문에서 우리는 영상화 결과의 방향 대칭적 모호성을 해결하고, 두 대의 RMC를 이용해 거리를 추정하는 방법을 제안한다. 그리고 이를 RMC 시뮬레이션 데이터를 이용하여 성능을 검증한다. Rotating modulation collimator(RMC) is a remote sensing technique for a radiation source. This paper introduces an RMC system model and its image reconstruction algorithm based on Kowash’s research. The reconstructed image can show the direction of a source. However, the distance to the source cannot be recovered. Moreover, the RMC image suffers from 180° ambiguity. In this paper, we propose a distance estimation method using two RMCs together with a solution to the ambiguity. We also demonstrate its performance using simulated RMC data.
정규화(regularization)을 이용한 RMC 영상화 알고리즘의 성능 향상
신영준(Youngjun Shin),김기현(Geehyun Kim),이계민(Gyemin Lee) 대한전자공학회 2016 대한전자공학회 학술대회 Vol.2016 No.6
Detecting orphan radiation sources poses important issues for national security and international nuclear safety. In this paper, we propose an improved image reconstruction algorithm using a regularization method. The proposed algorithm increases the sparsity in the reconstructed RMC images. To demonstrate the proposed algorithm, we performed Monte-Carlo experiments. Our algorithm successfully reduces the artifacts and improves the quality of the RMC images.