Development and validation of multiphysics PWR core simulator KANT

Taesuk Oh,Yunseok Jeong,Husam Khalefih,Yonghee Kim Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6

KANT (KAIST Advanced Nuclear Tachygraphy) is a PWR core simulator recently developed at Korea Advance Institute of Science and Technology, which solves three-dimensional steady-state and transient multigroup neutron diffusion equations under Cartesian geometries alongside the incorporation of thermal-hydraulics feedback effect for multi-physics calculation. It utilizes the standard Nodal Expansion Method (NEM) accelerated with various Coarse Mesh Finite Difference (CMFD) methods for neutronics calculation. For thermal-hydraulics (TH) calculation, a single-phase flow model and a one-dimensional cylindrical fuel rod heat conduction model are employed. The time-dependent neutronics and TH calculations are numerically solved through an implicit Euler scheme, where a detailed coupling strategy is presented in this paper alongside a description of nodal equivalence, macroscopic depletion, and pin power reconstruction. For validation of the steady, transient, and depletion calculation with pin power reconstruction capacity of KANT, solutions for various benchmark problems are presented. The IAEA 3-D PWR and 4-group KOEBERG problems were considered for the steady-state reactor benchmark problem. For transient calculations, LMW (Lagenbuch, Maurer and Werner) LWR and NEACRP 3-D PWR benchmarks were solved, where the latter problem includes thermal-hydraulics feedback. For macroscopic depletion with pin power reconstruction, a small PWR problem modified with KAIST benchmark model was solved. For validation of the multi-physics analysis capability of KANT concerning large-sized PWRs, the BEAVRS Cycle1 benchmark has been considered. It was found that KANT solutions are accurate and consistent compared to other published works.

External analysis-based fuzzy PLS model for prediction and monitoring in MBR

Oh, TaeSuk,Liu, Hongbin,Kim, MingJung,Lee, SeungChul,Yeo, Min-Kyeong,Yoo, ChangKyoo Informa UK (Taylor Francis) 2012 Desalination and Water Treatment Vol.43 No.1

漢代 愛情類 樂府民歌 硏究

吳台錫 한국중국학회 2002 中國學報 Vol.46 No.-

漢代愛情題材樂府有如下的特徵. 第一, 從題材類型方面, 漢樂府歌分爲五種: 戀愛與相思, 別離的情情, 失戀與怨望, 家庭裏的愛情問題, 婦女與社會矛楯. 第二, 漢代這類民歌如同當時一般的詩歌一樣, 逼眞表現出愛情生活中發生的種種感情. 然而??一般詩歌有所不同處. 一般詩歌一面表現人生的虛幻意識, 一面流干對酒當歌類的一回性的不良態度. 愛情類樂府 大略以直入愛情故事敍以表出自己的感情. 第三. 漢代愛情類樂府中多出離情故事的原因. 分析大規漠土木築适事業一定的關係. 第四, 一般來看, 中國古典詩 主要是以篇輻小的抒抒情時爲主, 專用敍事的是罕見的. 然而, 家族類以及社會類作品裏可見長篇敍事詩. 影??到後代敍事文學, 値得注意的. 其他小小的, 略而不言.

LEU+ loaded APR1400 using accident tolerant fuel cladding for 24-month two-batch fuel management scheme

Husam Khalefih,Taesuk Oh,Yunseok Jeong,Yonghee Kim Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7

In this work, a 24-month two-batch fuel management strategy for the APR1400 using LEU + has been investigated, where enrichments of 5.9 and 5.2 w/o are utilized in lieu of the conventional 4-5 w/o UO₂ fuel. In addition, an Accident Tolerant Fuel (ATF) clad based on the swaging technology is applied to APR1400 fuel assemblies. In this special ATF clad design, both outer and inner SS316 layers protect the conventional zircaloy clad. Erbia (Er₂O₃) is introduced as a burnable absorber with two-fold goals to lower the critical boron concentration in the long-cycle LEU + loaded core as well as to handle the LEU + fuel in the existing front-end fuel facilities without renewing the license. Two types of fuel assemblies with different loading of gadolinia (Gd₂O₃) are considered to control both the reactivity and the core radial power distribution. The erbia burnable absorber is uniformly admixed with UO₂ in all fuel pins except for the gadolinia-bearing ones. In this study, two core designs were devised with different erbia loading, and core performance and safety parameters were evaluated for each case in comparison with a core design without any burnable absorbers. The core analysis was done using the two-step method. First, cross-sections are generated by the SERPENT 2 Monte Carlo code, and the 3-D neutronic analysis is performed with an in-house multi-physics nodal code KANT.

Estimation and assessment of long-term drought outlook information using the long-term forecasting data

So, Jae-Min,Oh, Taesuk,Bae, Deg-Hyo 한국수자원학회 2017 한국수자원학회논문집 Vol.50 No.10

본 연구에서는 장기예보자료 기반의 장기 가뭄전망정보를 산정하고, 2015년 가뭄사상을 대상으로 활용성을 평가하였다. 이를 위해 ASOS 59개 지점의 관측강수량, GloSea5의 미래예측 및 과거재현 자료를 활용하였으며, 다양한 지속기간(3, 6, 9, 12개월)에 대한 SPI를 산정하였다. 또한 예보선행시간(1~6개월)에 따른 SPI와 관측자료 기반의 SPI 간의 ROC (Receiver Operating Characteristic)및 통계적 분석(상관계수, 평균제곱근 오차)을 수행하여 전망정보의 활용성을 평가하였다. ROC 분석결과, SPI(3)는 2개월, SPI(6)은 3개월, SPI(9)는 4개월, SPI(12)는 5개월까지 ROC score 약 0.70 이상으로 산정되었다. 예보선행시간별 상관계수 및 평균제곱근오차의 경우, 2개월 선행시간 SPI(3)은 0.60, 0.87, 4개월 선행시간 SPI(6)은 0.72, 0.95, 5개월 선행시간 SPI(9)는 0.75, 0.95, 6개월 선행시간 SPI(12)는 0.77, 0.89로 상관계수는 높게, 평균제곱근오차는 낮게 산정되어 활용성이 있는 것으로 판단된다. The objective of this study is to evaluate the long-term drought outlook information based on long-term forecast data for the 2015 drought event. In order to estimate the Standardized Precipitation Index (SPI) for different durations (3-, 6-, 9-, 12-months), we used the observation precipitation of 59 Automated Synoptic Observing System (ASOS) sites, forecast and hindcast data of GloSea5. The Receiver Operating Characteristic (ROC) analysis and statistical analysis (Correlation Coefficient, CC; Root Mean Square Error, RMSE) were used to evaluate the utilization of drought outlook information for the forecast lead-times (1~6months). As a result of ROC analysis, ROC scores of SPI(3), SPI(6), SPI(9) and SPI(12) were estimated to be over 0.70 until the 2-, 3-, 4- and 5-months. The CC and RMSE values of SPI(3), SPI(6), SPI(9) and SPI(12) for forecast lead-time were estimated as (0.60, 0.87), (0.72, 0.95), (0.75, 0.95) and (0.77, 0.89) until the 2-, 4-, 5- and 6-months respectively.

SPCPC에서 LDPC부호를 이용한 오류 정정

김성만(Sungman Kim),오태석(Taesuk Oh),김범곤(Bum Gon Kim),송희근(Hee Keun Song),김용철(Yong Cheol Kim) 한국방송·미디어공학회 2006 한국방송공학회 학술발표대회 논문집 Vol.2006 No.-

본 논문은 AWGN 채널상의 Single Parity Check(SPC) 다차원 product부호에서 LDPC(Low Density Parity Check)부호를 이용한 오류 정정의 성능을 제시한다. 기존 방법인 터보 부호 방식을 이용한 오류 정정과 비교하여 LDPC부호가 갖는 장점을 기술하고 실험을 통해 LDPC 부호를 이용한 오류 정정 성능도 터보부호와 대등함을 보인다.

Analysis and prediction of indoor air pollutants in a subway station using a new key variable selection method

JungJin Lim,유창규,YongSu Kim,TaeSuk Oh,MinJung Kim,OnYu Kang,김정태,김인원,김조천,Jae-Sik Jeon 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.8

A new key variable selection and prediction model of IAQ that can select key variables governing indoor air quality (IAQ), such as PM10, CO2, CO, VOCs and formaldehyde, are suggested in this paper. The essential problem of the prediction model is the question of which of the original variables are the most important for predicting IAQ. The next issue is determining the number of key variables that should be ranked. A new index of discriminant importance in the projection (DIP) of Fisher’s linear discriminant (FLD) is suggested for selecting key variables of the prediction models with multiple linear regression (MLR) and partial least squares (PLS), as well as for ranking the importance of input measurement variables on IAQ prediction. The prediction models were applied to a real IAQ dataset from telemonitoring data (TMS) in a metro system. The prediction results of the model using all variables were compared with the results of the model using only key variables of DIP. It shows that the use of our new variable selection method cannot only reduce computational effort, but will also enhance the prediction performances of the models.

A systematic model calibration methodology based on multiple errors minimization method for the optimal parameter estimation of ASM1

JungJin Lim,유창규,MinHan Kim,김민정,TaeSuk Oh,OnYu Kang,민부기,Ambati Seshagiri Rao 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.3

A one-step model calibration methodology of the activated sludge model no. 1 (ASM1) of a full-scale wastewater treatment plant (WWTP) is proposed. First, the key parameters among all parameters of the ASM1 model are selected by sensitivity analysis based on the effluent quality index. Second, multiple response surface methodology (MRSM) is conducted to find the optimal parameter values of the ASM1 model. Lastly, an MRSM analysis is conducted in order to determine the optimal parameter values. This study was conducted in order to develop a new systematic model calibration methodology that can greatly help the modeler to find the optimal solution by selecting the key parameters and optimizing the parameters. In two case studies of simple activated sludge process and a full-scale plant,the experimental results indicated that the calibrated models can improve the prediction quality of the ASM model and the efficiency of the modeling.

농업시설용 기능성필름 성능기준 설정을 위한 기상정보 분석

김영화 ( Younghwa Kim ),김형권 ( Hyungkwon Kim ),이태석 ( Taesuk Lee ),오성식 ( Sungsik Oh ),유영선 ( Youngsun Ryou ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.2

온실재배는 작물재배환경을 조절하여 기상환경에 영향 없이 작물재배가 가능하나 고온성 작물 재배시 발생되는 에너지 비용과 보온용 피복재로 인한 광투과성 저하가 우려될 수 있다. 시설원예 경영시 냉난방 에너지 절감방안은 에너지원 대체 방안과 보온성 향상 방안이 있으며 초기투자비용을 절감하기 위해서는 후자가 우선적으로 검토된다. 최근 피복재료 및 소재 발달로 인하여 보온과 광투과 목적을 위한 기능성 필름이 개발되고 있으며 일반 건축물에 적용할 경우 광투과를 제한해야하나 온실에 적용할 때에는 보온과 동시 광투과를 높여야하는 등 차이가 있어 농업분야 온실 환경에 맞는 성능 설정이 요구된다. 온실에 적용 가능한 기능성필름에 관한 연구는 전무한 실정이며 이에 따른 기능성 필름의 성능 설정을 위하여 우리나라 조도, 복사량 등의 일사정보 등의 기상자료 분석이 선행되어야한다. 본 연구에서는 최근 우리나라의 조도 및 복사량의 정보를 분석하였으며 농업시설 기능성필름의 요구 성능을 설정하는 기초자료로 활용될 것으로 기대한다.

장기예보자료를 활용한 장기 가뭄전망정보 산정 및 평가

소재민,오태석,배덕효,So, Jae-Min,Oh, Taesuk,Bae, Deg-Hyo 한국수자원학회 2017 한국수자원학회논문집 Vol.50 No.10

본 연구에서는 장기예보자료 기반의 장기 가뭄전망정보를 산정하고, 2015년 가뭄사상을 대상으로 활용성을 평가하였다. 이를 위해 ASOS 59개 지점의 관측강수량, GloSea5의 미래예측 및 과거재현 자료를 활용하였으며, 다양한 지속기간(3, 6, 9, 12개월)에 대한 SPI를 산정하였다. 또한 예보선행시간(1~6개월)에 따른 SPI와 관측자료 기반의 SPI 간의 ROC (Receiver Operating Characteristic)및 통계적 분석(상관계수, 평균제곱근 오차)을 수행하여 전망정보의 활용성을 평가하였다. ROC 분석결과, SPI(3)는 2개월, SPI(6)은 3개월, SPI(9)는 4개월, SPI(12)는 5개월까지 ROC score 약 0.70 이상으로 산정되었다. 예보선행시간별 상관계수 및 평균제곱근오차의 경우, 2개월 선행시간 SPI(3)은 0.60, 0.87, 4개월 선행시간 SPI(6)은 0.72, 0.95, 5개월 선행시간 SPI(9)는 0.75, 0.95, 6개월 선행시간 SPI(12)는 0.77, 0.89로 상관계수는 높게, 평균제곱근오차는 낮게 산정되어 활용성이 있는 것으로 판단된다. The objective of this study is to evaluate the long-term drought outlook information based on long-term forecast data for the 2015 drought event. In order to estimate the Standardized Precipitation Index (SPI) for different durations (3-, 6-, 9-, 12-months), we used the observation precipitation of 59 Automated Synoptic Observing System (ASOS) sites, forecast and hindcast data of GloSea5. The Receiver Operating Characteristic (ROC) analysis and statistical analysis (Correlation Coefficient, CC; Root Mean Square Error, RMSE) were used to evaluate the utilization of drought outlook information for the forecast lead-times (1~6months). As a result of ROC analysis, ROC scores of SPI(3), SPI(6), SPI(9) and SPI(12) were estimated to be over 0.70 until the 2-, 3-, 4- and 5-months. The CC and RMSE values of SPI(3), SPI(6), SPI(9) and SPI(12) for forecast lead-time were estimated as (0.60, 0.87), (0.72, 0.95), (0.75, 0.95) and (0.77, 0.89) until the 2-, 4-, 5- and 6-months respectively.