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MARS-KS 코드를 사용한 ATLAS 실험장치의 MSGTR-PAFS 사고 분석
정현준,김태완,Jeong, Hyunjoon,Kim, Taewan 한국안전학회 2021 한국안전학회지 Vol.36 No.3
Korea Atomic Energy Research Institute (KAERI) has been operating an integral effects test facility, the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS), according to APR1400 for transient experimental and design basis accident simulation. Moreover, based on the experimental data, the domestic standard problem (DSP) program has been conducted in Korea to validate system codes. Recently, through DSP-05, the performance of the passive auxiliary feedwater system (PAFS) in the event of multiple steam generator tube rupture (MSGTR) has been analyzed. However, some errors exist in the reference input model distributed for DSP-05. Furthermore, the calculation results of the heat loss correlation for the secondary system presented in the technical report of the reference indicate that a large difference is present in heat loss from the target value. Thus, in this study, the reference model is corrected using the geometric information from the design report and drawings of ATLAS. Additionally, a new heat loss correlation is suggested by fitting the results of the heat loss tests. Herein, MSGTR-PAFS accident analysis is performed using MARS-KS 1.5 with the improved model. The steady-state calculation results do not significantly differ from the experimental values, and the overall physical behavior of the transient state is properly predicted. Particularly, the predicted operating time of PAFS is similar to the experimental results obtained by the modified model. Furthermore, the operating time of PAFS varies according to the heat loss of the secondary system, and the sensitivity analysis results for the heat loss of the secondary system are presented.
딥러닝을 활용한 콘크리트의 공극률 예측모델과 공극률-탄산화 깊이의 상관관계 분석
정현준 ( Jeong Hyun-joon ),이건호 ( Lee Gun-ho ),지성우 ( Ji Seong-woo ),김수빈 ( Kim Su-bin ),김강수 ( Kim Kang-su ) 한국구조물진단유지관리공학회 2021 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.25 No.2
콘크리트의 탄산화는 공극률과 높은 상관관계를 가지나, 계측을 통한 공극률 측정은 일반적으로 비용 및 시간 소모가 크다. 따라서, 본 연구에서는 배합비와 압축강도만을 이용하여 공극률을 예측하는 딥러닝 모델을 개발하였으며, 예측한 공극률과 탄산화 깊이에 대한 실험데이터의 상관관계를 분석하였다.
캐리어 수명시간과 온도에 따른 수직형 절연 게이트 바이폴러 트랜지스터의 Forward Biased Safe Operating Area를 위한 설계 및 시뮬레이션
정현준(Hyunjoon Jeong),김태은(Taeeun Kim),하민우(Min-Woo Ha) 대한전기학회 2020 전기학회논문지 Vol.69 No.3
The forward biased safe operating area of insulated gate bipolar transistors (IGBTs) is important for stable and reliable operations. A parasitic thyristor latch-up has limited the on-state operation of the devices. In this manuscript, we reported the forward biased safe operating area of the vertical punch through IGBTs with various N buffer layers, carrier lifetimes, and temperatures. Increasing the thickness and doping concentration of the N buffer layer decreased the forward current and improved the forward biased safe operating area. The low forward current suppressed a parasitic thyristor latch-up. Reducing the carrier lifetime increased the forward bias safe operating area due to the enhanced recombination in the N buffer layer. At the high temperature, two conflicting mechanisms of the forward bias safe operating area were found. As the temperature rised, the forward bias safe operating area increased due to the channel scattering and forward current reduction. The forward biased safe operating area rather decreased at the high temperature because the parasitic thyristor easily triggered at the low collector voltage.
미세입자분산 액적의 고체면에서 충돌과 퍼짐현상에 관한 직접수치해석 기법개발
정현준(Hyun Jun Jeong),황욱렬(Wook Ryol Hwang),김종엽(Chongyoup Kim) 한국전산유체공학회 2008 한국전산유체공학회지 Vol.13 No.3
We present a numerical simulation technique and some preliminary results of the impact and spreading of a droplet containing particles on the solid substrate in 2D. We used the 2nd-order Adams-Bashforth / Crank-Nicholson method to solve the Navier-Stokes equation and employed the level-set method with the continuous surface stress for description of droplet spreading with interfacial tension. The impact velocity has been generated by the instantaneous gravity. The distributed Lagrangian-multipliers method has been combined for the implicit treatment of rigid particles and the discontinuous Galerkin method has been used for the stabilization of the interface advection equation. We investigated the droplet spreading by the inertial force and discussed effects of the presence of particles on the spreading behavior using an example problem. We observed reduced oscillation and spread for the particulate droplet.