감육 곡관의 붕괴거동에 미치는 곡관 굽힘각의 영향

나만균,김진원 대한기계학회 2006 大韓機械學會論文集A Vol.30 No.10

영광원전에서 가상 사고시 대기확산 평가

나만균,심영록,정철기,이경진,김승평,정성태,Na, Man-Gyun,Sim, Young-Rok,Jung, Chul-Kee,Lee, Goung-Jin,Kim, Soong-Pyung,Chung, Sung-Tai 대한방사선방어학회 2000 방사선방어학회지 Vol.25 No.2

현재 영광원전에서 정상운전중 기체 방사성물질의 대기확산 평가를 위해 XOQ_DW 코드가 이용되고 있다. 이 코드는 기본적으로 XOQDOQ 코드에 근거하여 개발되었으며, 정상운전 및 사고시 피폭평가를 수행하기 위하여, 사고시 대기확산을 평가하는 방법이 첨가되어야 한다. 사고시 대기확산을 평가하기 위해서 USNRC Reg. Guide 1.145에 기초하여 개발된 PAVAN 코드에 근거하여 가상 사고시 대기확산 코드인 XOQAR 코드가 개발되었다. 이 코드는 XOQ_DW 코드와의 인터페이스를 통하여 XOQ_DW 코드의 입력인 지형 모델 그리고 XOQ_DW 코드의 출력인 연평균 대기확산인자가 본 코드의 입력으로 이용되었다. 본 코드를 이용하여 제한구역경계와 저인구지대 경계에서 대기확산인자 값이 바다방향을 제외한 최대값은 각각 $1.33{\times}10^{-4}$와 $7.66{\times}10^{-6}$ sec/$m^3$이었다. 본 코드의 개발을 통하여 영광원전에서 정상운전 및 사고시 대기확산을 평가할 수 있는 코드 시스템을 갖추게 되었다. 또한 개발된 코드는 산악이 많은 우리나라 다른 발전소에 적용하기 위해 산악지형 입력변경을 통하여 적절히 사용될 수 있을 것이다. XOQ_DW code is currently used to assess the atmospheric dispersion fur the routine releases of radioactive gaseous effluents at Yonggwang nuclear power plants. This code was developed based on XOQDOQ code and an additional code is required to assess the atmospheric dispersion for potential accidental releases. In order to assess the atmospheric dispersion fer the accidental releases, XOQAR code has been developed by using PAVAN code that is based on Reg. Guide 1.145. The terrain data of XOQ_DW code inputs and the relative concentrations (X/Q) of XOQ_DW code outputs are used as the inputs of the XOQAR code through the interface with XOQ_DW code. By using this code, the maximum values of X/Q at exclusion area and low population zone boundaries except for sea areas were assessed as $1.33{\times}10^{-4}$ and $7.66{\times}10^{-6}$ sec/$m^3$, respectively. Through the development of this code, a rode system is prepared for assessing the atmospheric dispersion for the accidental releases as well as the routine releases. This developed code ran be used for other domestic nuclear power plants by modifying the terrain input data.

PREDICTION OF RESIDUAL STRESS FOR DISSIMILAR METALS WELDING AT NUCLEAR POWER PLANTS USING FUZZY NEURAL NETWORK MODELS

나만균,김진원,DONG HYUK LIM 한국원자력학회 2007 Nuclear Engineering and Technology Vol.39 No.4

A fuzzy neural network model is presented to predict residual stress for dissimilar metal welding under various welding conditions. The fuzzy neural network model, which consists of a fuzzy inference system and a neuronal training system, is optimized by a hybrid learning method that combines a genetic algorithm to optimize the membership function parameters and a least squares method to solve the consequent parameters. The data of finite element analysis are divided into four data groups, which are split according to two end-section constraints and two prediction paths. Four fuzzy neural network models were therefore applied to the numerical data obtained from the finite element analysis for the two end-section constraints and the two prediction paths. The fuzzy neural network models were trained with the aid of a data set prepared for training (training data), optimized by means of an optimization data set and verified by means of a test data set that was different (independent) from the training data and the optimization data. The accuracy of fuzzy neural network models is known to be sufficiently accurate for use in an integrity evaluation by predicting the residual stress of dissimilar metal welding zones.

원전 고등제어 알고리즘 설계를 위한 소규모 시뮬레이터 개발

나만균,심영록,신선호,노희천 조선대학교 에너지.자원신기술연구소 2003 에너지·자원신기술연구소 논문지 Vol.25 No.2

There has been a difficulty in implementing control algorithms (including even proportional-integral-derivative control algorithms) designed to verify and test to many small-scale simulators. In particular, it was almost impossible to implement advanced control algorithms to them. Therefore, it is required to develop a new simulator that facilitates the implementation of advanced control algorithms and the interface between different kinds of application programs. The objective of this work is to improve the existing small-scale simulator (FISA-2/WS) for the Kori unit 2 nuclear power plant and thus enable advanced control algorithms to be tested and verified by being applied to it. The developed simulator consists of FORTRAN, Visual C++, and MATLAB programs and an advanced control method using a receding horizon control method was applied to it to control the steam generator water level.

ROBUST CONTROLLER DESIGN FOR THE NUCLEARREACTOR POWER BY EXTENDED FREQUENCYRESPONSE METHOD

나만균,이윤준 한국원자력학회 2006 Nuclear Engineering and Technology Vol.38 No.6

제어모드 순위 자동 선정에 관한 연구

나만균,정동원,신선호 조선대학교 에너지.자원신기술연구소 2003 에너지·자원신기술연구소 논문지 Vol.25 No.1

제어계통의 고신뢰도는 제어 알고리즘의 강인성 및 성능의 향상으로 표현될 수 있으며, 고등 제어 알고리즘의 개발과 진단을 통한 발전소 조건의 변화에 따른 적절한 제어모드를 선정하므로써 달성될 수 있을 것이다. 본 연구에서는 여러 제어 알고리즘의 라이브러리로부터 요구된 필수 요건을 반드시 만족시키면서 목적 비용함수를 최소화하는 제어모드 순위 선정 자동화 기술을 개발하였다 개발된 방법은 발전소 상태의 변화 (운전조건의 변화, 기기고장 및 이상상태 등이 진단기술에 의하여 탐지), 필수 요건 혹은 최적화 요건의 변화에 의하여 적절한 제어모드 순위를 결정하여 운전원에게 제시하므로써 적절한 조치를 취하게 하거나 필요한 정보를 제공하여 준다. High reliability of control systems can be expressed as enhancement of their robustness and performance and can be accomplished by designing advanced control algorithms and selecting appropriate control modes according to changes of plant conditions through diagnostics. In this work, by combining control and diagnostic algorithms, we have developed the automatic design technology of control systems that candetermine control mode priority among a variety of control algorithm libraries according to operating conditions and key requirements of plants. The developed method enables operators to take appropriate actions or provide necessary information to operators by determining the control mode priority according to changes of key and optimizing requirements and/or changes in the states of nuclear power plan.

DESIGN OF A PWR POWER CONTROLLER USINGMODEL PREDICTIVE CONTROLOPTIMIZED BY A GENETIC ALGORITHM

나만균,IN JOON HWANG 한국원자력학회 2006 Nuclear Engineering and Technology Vol.38 No.1

DEVELOPMENT OF A RECONFIGURABLE CONTROL FOR AN SP-100 SPACE REACTOR

나만균,BELLE R. UPADHYAYA 한국원자력학회 2007 Nuclear Engineering and Technology Vol.39 No.1

In this paper, a reconfigurable controller consisting of a normal controller and a standby controller is designed to control the thermoelectric (TE) power in the SP-100 space reactor. The normal controller uses a model predictive control (MPC) method where the future TE power is predicted by using support vector regression. A genetic algorithm that can effectively accomplish multiple objectives is used to optimize the normal controller. The performance of the normal controller depends on the capability of predicting the future TE power. Therefore, if the prediction performance is degraded, the proportional-integral (PI) controller of the standby controller begins to work instead of the normal controller. Performance deterioration is detected by a sequential probability ratio test (SPRT). A lumped parameter simulation model of the SP-100 nuclear space reactor is used to verify the proposed reconfigurable controller. The results of numerical simulations to assess the performance of the proposed controller show that the TE generator power level controlled by the proposed reconfigurable controller could track the target power level effectively, satisfying all control constraints. Furthermore, the normal controller is automatically switched to the standby controller when the performance of the normal controller degrades.

A SOFT-SENSING MODEL FOR FEEDWATER FLOW RATE USING FUZZY SUPPORT VECTOR REGRESSION

나만균,HEON YOUNG YANG,DONG HYUK LIM 한국원자력학회 2008 Nuclear Engineering and Technology Vol.40 No.1

Most pressurized water reactors use Venturi flow meters to measure the feedwater flow rate. However, fouling phenomena, which allow corrosion products to accumulate and increase the differential pressure across the Venturi flow meter, can result in an overestimation of the flow rate. In this study, a soft-sensing model based on fuzzy support vector regression was developed to enable accurate on-line prediction of the feedwater flow rate. The available data was divided into two groups by fuzzy cmeans clustering in order to reduce the training time. The data for training the soft-sensing model was selected from each data group with the aid of a subtractive clustering scheme because informative data increases the learning effect. The proposed soft-sensing model was confirmed with the real plant data of Yonggwang Nuclear Power Plant Unit 3. The root mean square error and relative maximum error of the model were quite small. Hence, this model can be used to validate and monitor existing hardware feedwater flow meters.

퍼지 논리 추론 방법을 이용한 사고시 대기확산 평가 개선

나만균,심영록,김숭평 대한방사선 방어학회 2001 방사선방어학회지 Vol.26 No.1

사고시 대기확산을 평가하기 위해서 USNRC Reg. Guide 1.145에 기초하여 개발된 PAVAN과 XOQAR 코드는 X/Q 값을 계산할 때, 누적빈도에 대하여 X/Q 값이 log-normal 용지에 그려진다. 이 그래프에서 가장 높은 X/Q 값으로부터 시작하여 이 점으로부터 10개의 X/Q을 포함하는 영역내의 모든 다른 점 사이와 경사를 비교하여 가장 작은 음의 경사를 갖는 선을 생성하는 계수들이 저장되며, 이 선의 끝점이 다음 영역의 시작점으로 이용되어 반복적으로 선이 그려진다. 이와 같이 그려진 선을 이용하여 누적빈도 0.5%, 5% 혹은 50%에 상응하는 X/Q 값이 계산되어, 사고 후 0∼2 시간의 X/Q 값으로 이용되며 매우 보수적인 경향을 갖게 된다. 본 논문에서는 퍼지 논리 추론계통을 이용하여 누적빈도에 대한 X/Q 값의 비선형 보간을 수행하였다. 퍼지 논리 추론계통은 비선형 보간을 위해 탁월한 방법으로 알려져 있다. 제안된 방법을 영광 원자력발전소의 잠재적 방사성물질 누출에 적용한 결과, 좀 더 현실적인 값을 제공하는 것으로 확인되었다. In order to assess the atmospheric dispersion for the accidental releases of nuclear power plants, in calculating X/Q values in the XOQAR and PAVAN codes which are based on Reg. Guide 1.145, the X/Q and frequency values are plotted on log-normal paper. Starting with the highest X/Q value of this plot, the codes compare the slope of the line drawn from this point to every other point within an increment containing ten X/Q values. If there are fewer than ten values, only the number available are used. The coefficients that produce the line with the least negative slope are saved. The end point of this line is used as the next starting point, from which slopes to the points within the next increment, containing ten X/Q values, are compared. The X/Q values corresponding to the cumulative frequency values 0.5%, 5% or 50% are calculated to search fur the 0∼2 hour X/Q values that tends to be a very conservative value. In this work, a fuzzy logic inference method is used for nonlinear interpolation of the X/Q values versus the cumulative frequency. The fuzzy logic inference method is known to be a good technique for nonlinear interpolation. The proposed method was applied to a potential accidential radioactive release of the Yonggwang nuclear power plant, which gives more realistic X/Q values.