• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.505-508
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• 2006

Recently, concern for tidal power is being increased by newly recycled energy. It is important to decide on the maximum power estimate operation and it's stop by applying the difference of water level between tide level and artificial reservoir for the administration of tidal development. For maximum output of power through turbine generator, administrative variables and process on efficiency of hydraulic turbine and inflow discharge of reservoir is quite complicated because it is run through the connection of discharge-gate and turbine On the development of this model, the administrative process is decided, Operation block is presented for it's maximum power estimate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.247-248
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• 2015

Wind turbines causes instabilities on the grid as their penetration increase. To mitigate harmful effects from wind turbines, transmission system operator(TSO) set up some requirements to obligate for wind generation operator for grid connection. So wind farm management system(WFMS) has important role to follow requirement from TSO, WFMS calculates available real power by considering wake effects, and dispatches real power order to each wind turbine in wind farm to optimize for decreasing load fatigue. To verify operation of WFMS, real-time simulator(RTS) is necessary. This paper deals with RTS configuration to verify WFMS operation. RTS includes wind farm model and power flow code. Normally, wind farm equivalent simple model makes wind turbines in wind farm to one wind turbine mode which cannot verify power flow in wind farm and WFMS operation. Thus, this paper makes wind farm model using simple wind turbine model with transfer function. Matlab is used for make power flow code and wind farm model to impose RTS and those model is certified by PSCAD/EMTDC.

• Nuclear Engineering and Technology
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• 제48권5호
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• pp.1140-1153
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• 2016

Since the inception of nuclear power as a commercial energy source, safety has been recognized as a prime consideration in the design, construction, operation, maintenance, and decommissioning of nuclear power plants. The release of radioactivity to the environment requires the failure of multiple safety systems and the breach of three physical barriers: fuel cladding, the reactor cooling system, and containment. In this study, nuclear reactor containment pressurization has been modeled in a large break-loss of coolant accident (LB-LOCA) by programming single-cell and multicell models in MATLAB. First, containment has been considered as a control volume (single-cell model). In addition, spray operation has been added to this model. In the second step, the single-cell model has been developed into a multicell model to consider the effects of the nodalization and spatial location of cells in the containment pressurization in comparison with the single-cell model. In the third step, the accident has been simulated using the CONTAIN 2.0 code. Finally, Bushehr nuclear power plant (BNPP) containment has been considered as a case study. The results of BNPP containment pressurization due to LB-LOCA have been compared between models, final safety analysis report, and CONTAIN code's results.

• 한국방재학회 논문집
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• 제4권1호
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• pp.33-40
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• 2004

본 연구에서는 치수방재 효과를 향상시키기 위한 단일댐운영 모형을 개발하였으며, 제어기법은 퍼지제어 기법을 사용하였다. 본 모형은 저수지 수위와 유입량을 기준으로 제어규칙을 설정하였으며 방류량을 결정하는 제어기준에 따라 Fuzzy I, II, III의 세가지 모형을 개발하였다. Fuzzy I 모형은 6개의 제어규칙에 의해 홍수조절만을 고려한 것이고, Fuzzy II 모형은 I 모형의 치수효과를 가지면서도 홍수후의 저수위를 상승시켜 이수적인 효과도 얻기 위한 모형이며, Fuzzy III 모형은 적응제어모형으로 제어규칙을 9개로 세분화하여 치수효과와 이수효과를 동시에 거둘 수 있도록 한 모형이다.

• 한국초등과학교육학회지:초등과학교육
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• 제23권4호
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• pp.273-278
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• 2004

According to Piaget, children aged 11 are in the middle of concrete operation period and formal operation period. So, it is necessary to adopt the Learning Cycle Model (LCM) which helps students improve their cognitive development. After determining the test for the Science Concept of Matter (SCOM), the experimental group showed higher average than the comparative group in the post-test. In the sound understanding, the experimental group showed higher ratio than the comparative group. And in the ratio of imperfect, wrong understanding and no response, the experimental group was lower than the comparative group. On the questions that were needed the complicated inquiry, many students of both groups still couldn't find the fundamental cause. In forming the scientific conceptualization, there was a meaningful difference (p < .001) after post-test Analysis of Covariance (ANCOVA) with pre-test result. After determining the test for the Test Inquiry Science Process (TISP), the experimental group showed higher average than the comparative group in the post-test. In the category of basic inquiry process which is needed in concrete operation, there was a meaningful difference (p < .05). In the category of unified inquiry process which is needed in formal operation, they showed no meaningful difference (p > .05). Therefore, applying the LCM to the chapter of 'Solution and Dissolving' is more effective on improving the scientific conceptualization and on helping the concrete operation abilities than the teacher centered learning.

• 한국기계가공학회지
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• 제7권2호
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• pp.23-30
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• 2008

As a basic machining process, turning is a widely used machining process in which a single-point cutting tool removes material from the surface of a rotating material. A common method of evaluating machining performance is to measure the surface roughness. In a turning operation, it is important to select cutting conditions for achieving high cutting performance. As a rule, cutting conditions can be classified into feed rate, depth of cut and insert radius. While cutting process even though cutting conditions are optimized, the average roughness can be deterioration due to wear of the cutting tool edge. In this study, the aim is to maintain the average roughness even though the cutting condition is irregularly changing within the predictable range due to the working environment. First, the surface roughness model influenced by cutting conditions is constructed based on the experimental results in a turning operation, Second, applying the sliding mode control theory to the turning operation model which is composed of the surface roughness model and the motor transfer function, the surface roughness is closed to the desired value. Finally, the effectiveness of this approach is demonstrated through the computer simulation.

• Geomechanics and Engineering
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• 제30권3호
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• pp.273-280
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• 2022

A certain amount of random vibration excitation to subway track is caused by subway operation. This excitation is transmitted through track foundation, tunnel, soil medium, and ground building to the ground and ground structure, causing vibration. The vibration affects ground building. In this study, the results of ANSYS numerical simulation was used to establish back-propagation (BP) neural network model. Moreover, a back-propagation neural network model consisting of five input neurons, one hidden layer, 11 hidden-layer neurons, and three output neurons was used to analyze and calculate the vertical Z-vibration level of New Capital's ground buildings of Qingdao Metro phase I Project (Line M3). The Z-vibration level under different working conditions was calculated from monolithic roadbed, steel-spring floating slab roadbed, and rubber-pad floating slab roadbed under the working condition of center point of 0-100 m. The steel-spring floating slab roadbed was used in the New Capital area to monitor the subway operation vibration in this area. Comparing the monitoring and prediction results, it was found that the prediction results have a good linear relationship with lower error. The research results have good reference and guiding significance for predicting vibration caused by subway operation.

• 멤브레인
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• 제14권1호
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• pp.75-84
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• 2004

폴리아미드계 역삼투 분리막의 투과성능을 비교하기 위하여 NaCl과 NaOCl을 함유하는 혼합용액을 공급수로 사용하여 연속운전과 단속운전 하에서 실험하여 보았다. 이 결과를 가지고 막 이동 모델의 선택적 적용이 가능함을 제시하고자 하였으며 투과 성능 분석 결과, 용액 확산 모델과 선흡착-모세관이동 모델이 운전 모드에 따라 상대적으로 유용함을 볼수 있었다. 연속 운전에서는 선흡착-모세관이동 모델을, 단속 운전에서는 용액 확산 모델을 따름을 알 수 있었다 NaOCl에 의한 표면 변화를 SEM 사진을 통하여 확인 할 수 있었다. 연속운전 후의 막은 염소 투과 결과 표면에서 부분적인 ridge and valley 구조가 나타났으며 단속 운전 후의 막은 표면 전반에서 변성이 일어난 것을 볼 수 있었다.

• 한국안전학회지
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• 제36권5호
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• pp.79-85
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• 2021

A standard engineering model that reflects the current organization system and engineering operation process of domestic nuclear power plants was developed based on the Standard Nuclear Performance Model developed by the American Nuclear Energy Association. The level 0 screen, which is the main screen of the engineering model computer system, consisted of an object tree structure, which provided information that is phased down from a higher structure level to a lower structure level (i.e., level 3). The level 1 screen provided information related to the sub-process of the engineering operation, whereas the Level 2 screen provided information related to each engineering operation activity. In addition, the Level 2 screen provided additional functions, such as linking electronic procedures/guidelines, providing electronic performance forms, and connecting legacy computer systems (such as total equipment reliability monitoring system, configuration management systems, technical information systems, risk monitoring systems, regulatory information, and electronic drawing system). This screen level increased the convenience of user's engineering tasks by implementing them. The computerization of an engineering model that connects the entire engineering tasks of an establishment enables the easy understanding of information related to the engineering process before and after the operation, and builds a foundation for the enhancement of the work efficiency and employee capacity. In addition, KHNP developed an online training module, which operates as an e-learning process, on the overview and utilization of a standard engineering model to expand the understanding of standard engineering models by plant employees and to secure competitiveness.

• 한국수자원학회논문집
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• 제33권6호
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• pp.733-744
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• 2000

불확실한 저수지 유입량과 수요량 때문에 최적의 저수지 조작기준은 정량화하기 쉽지 않다. 그렇지만 저수지 조작에 일정 수요를 충족시키면서 모의 발생시킨 유입량 시계열을 반영함으로써 음해 추계적 최적화 접근법을 이용하면 조작기준은 작성 가능하다. 이에 본 연구에서는 한강수계 7개 저수지 계통에 적절하도록 수력발전 최대화를 선형추적으로 모형화하고 최적제어를 이용하여 최적조작을 수행하였다. 이 때 2001년 수도권 용수수요를 만족시키도록 한 최적 조작 모형에는 다지점 마코브 모형에 의해 모의 발생된 유입량 자료가 입력된다. 그리고 최적 결과에 대하여 회구 분석과 통계 분석을 수행하여 월별 조작기준을 작성하고 계절별 저수위별 확률을 제시하였다. 이때 상대적으로 저수용량이 커서 조절능력이 좋은 화천댐, 소양강댐, 충주댐은 저류와 방류의 회귀 관계가 잘 형성되었다. 작성된 조작기준으로 실제 운영 기간동안에 대하여 모의조작을 수행하여 그 효율성을 검증하였다.