• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4504-4517
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• 2023

After a loss of coolant accident (LOCA) in the prestressed concrete containment vessels (PCCVs) of nuclear power plants, the coupling of temperature and pressure can significantly affect the mechanical properties of the PCCVs. However, there is no consensus on how this coupling affects the failure mechanism of PCCVs. In this paper, a simplified finite element modeling method is proposed to study the effect of temperature and pressure coupling on PCCVs. The experiment results of a 1:4 scale PCCV model tested at Sandia National Laboratory (SNL) are compared with the results obtained from the proposed modeling approach. Seven working conditions are set up by varying the internal and external temperatures to investigate the failure mechanism of the PCCV model under the coupling effect of temperature and pressure. The results of this paper demonstrate that the finite element model established by the simplified finite element method proposed in this paper is highly consistent with the experimental results. Furthermore, the stress-displacement curve of the PCCV during loading can be divided into four stages, each of which corresponds to the damage to the concrete, steel liner, steel rebar, and prestressing tendon. Finally, the failure mechanism of the PCCV is significantly affected by temperature.

• 한국초전도ㆍ저온공학회논문지
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• 제26권2호
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• pp.19-23
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• 2024

3D printing has the advantage of being able to process various types of parts by layering materials. In addition to these advantages, 3D printing technology allows models to be processed quickly without any special work that can be used in different fields to produce workpieces for various purposes and shapes. This paper deals to not only increase the utilization of 3D printing technology, but also to revitalize 3D printing technology in applications that require similar cryogenic environments. The goal of this study is to identify the mechanical properties of polylactic acid and photopolymer resin processed by Fused Deposition Modeling (FDM) and Digital Light Processing (DLP) respectively. The entire process is meticulously examined, starting from getting the thermal contraction using an extensometer. A uniaxial tensile test is employed, which enables to obtain the mechanical properties of the samples at both room temperature (RT) and cryogenic temperature of 77 K. As the results, photopolymer resin exhibited higher tensile properties than polylactic acid at RT. However, at cryogenic temperatures (77 K), the photopolymer resin became brittle and failure occurred due to thermal contraction, while polylactic acid demonstrated superior tensile properties. Therefore, polylactic acid is more suitable for lower temperatures.

• 한국지능시스템학회논문지
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• 제23권5호
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• pp.412-417
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• 2013

태양광 발전 시스템의 해석적 모델링은 시스템의 동특성을 예측하거나 고장검출 및 진단 등과 같은 고급 공학 기술에 중요하게 적용할 수 있어 최근 많은 각광을 받고 있다. 본 논문은 대용량 학습 데이터를 갖는 태양광 발전 시스템에 대한 확률론적 모델링을 제시한다. 우선 태양광 일사량과 온도 입력 변수에 대한 태양광 시스템의 출력 전력과의 입출력 함수관계를 정의한다. 이 함수관계를 바탕으로 세 확률변수(일사량, 온도, 전력)에 대하여 조건부 확률 식으로 표현한다. 조건부 확률 분포 추정은 대용량 데이터 시스템에 적합한, 전체 표본 데이터 수 대비 관련 변수의 경우의 수에 대한 비율로 나타내었다. 추정한 확률분포를 통해 평균값 이론을 적용하여 시스템의 출력을 추정하게 된다. 본 논문에서 제안한 모델링 기법은 두 태양광 발전 단지의 사례 연구를 통해 성능을 검증하였다.

• 한국연소학회지
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• 제22권2호
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• pp.27-35
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• 2017

This paper reviews the previous industrial solid bed process simulations to provide a better understanding of the modeling approaches to the particle reactions in the bed. Previous modeling studies on waste incinerator, iron ore sintering bed, blast furnace, iron ore pellet indurator, and biomass combustor can be seen on the common ground of unsteady 1-D modeling scheme. Approaches to the particle reaction modeling have been discussed in terms of the status of solid particles in the bed, types of reaction progression in a particle, and the consideration of the intra-particle temperature gradient.

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.1046-1050
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• 2004

Six physical properties (enthalpy, density, decomposition temperature, solubility in water, pKa values, and hydronium potential) were examined by molecular modeling techniques. The molecular connectivity index, Wiener distance index, and Ad hoc descriptor are employed as structural parameters to encode information about branching, size, cyclization, unsaturation, heteroatom content, and polarizability. This paper examines the correlation of the molecular modeling techniques parameters and the physicochemical properties of amino acids. As a results, calculated values were in agreement with experimental data in the above six physical properties of amino acids and the molecular connectivity index was superior to the other indices in fitting the calculated data.

• Journal of Electrical Engineering and Technology
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• 제6권2호
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• pp.270-274
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• 2011

This paper presents a parameterized simulation program with integrated circuit emphasis (SPICE) model of a two-level microbolometer based on negative-temperature-coefficient thin films, such as vanadium oxide or amorphous silicon. The proposed modeling begins from the electric-thermal analogy and is realized on the SPICE modeling environment. The model consists of parametric components whose parameters are material properties and physical dimensions, and can be used for the fast design study, as well as for the co-design with the readout integrated circuit. The developed model was verified by comparing the obtained results with those from finite element method simulations for three design cases. The thermal conductance and the thermal capacity, key performance parameters of a microbolometer, showed the average difference of only 4.77% and 8.65%, respectively.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.1163-1168
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• 2013

In this paper, Adaptive Neuro-Fuzzy Inference System (ANFIS) is applied for modeling and simulation of DC characteristic of cylindrical Silicon Nanowire Transistor (SNWT). Device Geometry parameters, terminal voltages, temperature and output current were selected as the main factors of modeling. The results obtained are compared with numerical method and a good match has been observed between them, which represent accuracy of model. Finally, we imported the ANFIS model as a voltage controlled current source in a circuit simulator like HSPICE and simulated a SNWT inverter and common-source amplifier by this model.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제21회 KOSCO SYMPOSIUM 논문집
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• pp.24-32
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• 2000

A brief introduction is given on the conditional moment closure model for turbulent nonpremixed combustion. It is based on the transport equations derived through a rigorous mathematical procedure for the conditionally averaged quantities and appropriate modeling forms for conditional scalar dissipation rate, conditional mean velocity and reaction rate. Examples are given for prediction of NO and OH in bluffbody flames, soot distribution in jet flames and autoignition of a methane/ethane jet to predict the ignition delay with respect to initial temperature, pressure and fuel composition. Conditional averaging may also be a powerful modeling concept in other approaches involved in turbulent combustion problems in various different regimes.

• 한국정보통신학회논문지
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• 제9권2호
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• pp.316-321
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• 2005

새로운 전류원 모델과 이 전류원 모델에 대응하는 파라메터의 직접추출 방법을 제안하였다. 전류원 모델파라메터를 위한 정확하고 해석적인 계산방법을 유도하였다. 이러한 해석적 모델링 방법을 기반으로 스케일 가능한 H8T 모델을 만드는 방법에 적용되었다. 단조함수적 스케일링이 가능하도록 하도록 하기 위해, 모델링 과정에서, 몇몇 파라메터들의 증복성(redunduncy)을 제거하는 방법을 개발하였다. 이러한 방법에 기반을 둔 모델을 실제 소자에 적용 했을때, 소자의 온도, 바이어스 및 크기변화를 잘 예측할 수 있었다.

• 한국초전도ㆍ저온공학회논문지
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• 제15권3호
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• pp.9-12
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• 2013

Current-voltage characteristic models of superconducting material are suggested by many researchers. These current-voltage characteristic models are important because they can be used for design or simulation of superconductor devices. But widely used current-voltage models of superconductor wire still have some limitations. For example, a standard E-J power model has no parameters related with stabilizer's resistance in superconductor wire. In this paper, a current-voltage characteristic modeling method for high temperature superconductor (HTS) tape with considering the effect of stabilizer is introduced. And a current-voltage characteristic of a HTS tape is measured under different stabilizer conditions. Those measured current-voltage characteristics of the HTS tape modeled with proposed modeling method and the modeling results are compared.