• 조명전기설비학회논문지
• /
• 제26권5호
• /
• pp.1-12
• /
• 2012

In order to reduce energy consumption and greenhouse gas emission in building domain, thermal insulation of building is being enhanced. In a well insulated and tightened environment, internal heat gain caused by solar radiation, luminaires, electronic appliances and metabolism can be more important to thermal condition of building. This paper presents mathematical/physical models of quasi-adiabtic room and lighting fixtures using heat balance equation and thermal-electric analogy to quantify and modelize the heat gain due to luminaires. Experimental results are used to identify thermal parameters of theoretical models. And simulation results of models using Matlab/Simulink are conducted to verify the models and to investigate the thermal effect of lighting fixtures into quasi-adiabatic room.

• Advances in aircraft and spacecraft science
• /
• 제5권1호
• /
• pp.141-164
• /
• 2018

In this paper, the thermal effect on buckling and free vibration characteristics of functionally graded (FG) size-dependent Timoshenko nanobeams subjected to an in-plane thermal loading are investigated by presenting a Navier type solution for the first time. Material properties of FG nanobeam are supposed to vary continuously along the thickness according to the power-law form and the material properties are assumed to be temperature-dependent. The small scale effect is taken into consideration based on nonlocal elasticity theory of Eringen. The nonlocal equations of motion are derived based on Timoshenko beam theory through Hamilton's principle and they are solved applying analytical solution. According to the numerical results, it is revealed that the proposed modeling can provide accurate frequency results of the FG nanobeams as compared to some cases in the literature. The detailed mathematical derivations are presented and numerical investigations are performed while the emphasis is placed on investigating the effect of the several parameters such as thermal effect, material distribution profile, small scale effects, aspect ratio and mode number on the critical buckling temperature and normalized natural frequencies of the temperature-dependent FG nanobeams in detail. It is explicitly shown that the thermal buckling and vibration behaviour of a FG nanobeams is significantly influenced by these effects. Numerical results are presented to serve as benchmarks for future analyses of FG nanobeams.

• 한국결정성장학회지
• /
• 제7권3호
• /
• pp.504-513
• /
• 1997

우주왕복선과 같은 발전된 비행체의 열 차단 시스템(TPS)에서의 이상적인 후보로는 섬유질 내화성 복합 절연체(FRCI)와 AETB(Alumina-Enhanced Thermal Barrier)가 있다. 이중, 본 연구에서는 FRCI의 열 펄스에 대한 열적응답을 실리카와 비교하여 수학적으로 모델링하여 전사모사 하였다. 또, 100~2000 K의 온도범위에서 FRCI의 여러 변수에 따른 각 열전도도를 계산하여 보았다.

• Nuclear Engineering and Technology
• /
• 제49권6호
• /
• pp.1219-1225
• /
• 2017

In this work, a scalable algorithm for model calibration in nuclear engineering applications is presented and tested. The algorithm relies on the construction of surrogate models to replace the original model within the region of interest. These surrogate models can be constructed efficiently via reduced order modeling and subspace analysis. Once constructed, these surrogate models can be used to perform computationally expensive mathematical analyses. This work proposes a surrogate based model calibration algorithm. The proposed algorithm is used to calibrate various neutronics and thermal-hydraulics parameters. The virtual environment for reactor applications-core simulator (VERA-CS) is used to simulate a three-dimensional core depletion problem. The proposed algorithm is then used to construct a reduced order model (a surrogate) which is then used in a Bayesian approach to calibrate the neutronics and thermal-hydraulics parameters. The algorithm is tested and the benefits of data assimilation and calibration are highlighted in an uncertainty quantification study and requantification after the calibration process. Results showed that the proposed algorithm could help to reduce the uncertainty in key reactor attributes based on experimental and operational data.

• 항공우주시스템공학회지
• /
• 제4권4호
• /
• pp.28-36
• /
• 2010

Current tanks have been developed to increase mobility and firepower, and its maximum range and destructive power are improved. This great change causes remained vibration of a gun barrel after firing. For this reason, people are trying to control vibration of gun barrel effectively. This thesis presents a modeling method and analysis results for gun barrel by using a thermal shroud as an absorber mass. DTS(Dynamically Tuned Shroud) is a vibration damping system using a thermal shroud as an added mass for decreasing remained vibration. The model has an advantage that the gun barrel's vibration can be decreased by dissipating a kinetic energy of thermal shroud without install an additional dynamic absorber to tip of the gun barrel. For analyzing the damping performance of the DTS, We derived an equation of motion of the barrel after setting a mathematical modeling, and found out the frequency analysis and tendency according to stiffness ratio between barrel and shroud.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
• /
• pp.181-188
• /
• 2006

Operation parameters for large scale industrial facility such as iron making plant are carefully selected through elaborate tests and monitoring rather than through a mathematical modeling. One of the recent progresses for better energy utilization in iron ore sintering process is the distribution pattern of fuel inside a macro particle which is formed with fines of iron ore, coke and limestone. Results of model tests which have been used as a basis for the improved operation in the field are introduced and a theoretical modeling study is presented to supplement the experiment-based approach with fundamental arguments of physical modeling, which enables predictive computation beyond the limited region of tests and adjustment. A single fuel particle model along with one-dimensional bed combustion model of solid particles are utilized, and thermal processes of combustion and heat transfer are found to be dominant consideration in the discussions of productivity and energy utilization in the sintering process.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.1201-1204
• /
• 2004

This paper suggests a DCS (Distributed Control System) model for steam temperature system of the thermal power plant. The model calculated within sectional range is linear. In order to calculate mathematical models, the system is partitioned into two or three sectors according to its thermal conditions, that is, saturated water/steam and superheating state. It is divided into three sections; water supply, steam generation and steam heating loop. The steam heating loop is called 'superheater' or steam temperature system. Water spray supply is the control input. A first order linear model is extracted. For linear approach, sectional linearization is achieved. Modeling methodology is a decomposition-synthetic technique. Superheater is composed of several tube-blocks. For this block, linear input-output model is to be calculated. Each tiny model has its transfer function. By expanding these block models to total system, synthetic DCS linear models are derived. Control instrument include/exclude models are also considered. The resultant models include thermal combustion conditions, and applicable to practical plant engineering field.

• Advances in aircraft and spacecraft science
• /
• 제9권1호
• /
• pp.59-68
• /
• 2022

The physical and mathematical foundations of the heat-shielding composite materials functioning under the conditions of aerodynamic heating of aircraft, as well as under the conditions of the point effect of high-energy radiation are considered. The problem of deformation of a thin shallow shell under the action of a local temperature field is approximately solved. Such problems arise, for example, in the case of local destruction of heat-protective coatings of aircraft shells. Then the aerodynamic heating acts directly on the load-bearing shell of the structure. Its destruction inevitably leads to the death of the entire aircraft. A methodology has been developed for the numerical solution of the entire complex problem on the basis of economical absolutely stable numerical methods. Multiple results of numerical simulation of the thermal state of the locally heated shallow shell under conditions of its thermal destruction at high temperatures have been obtained.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 춘계학술대회논문집
• /
• pp.114-117
• /
• 2006

The air filter in engine intake system has a function of filtrating the dirt in the scavenging air as well as attenuating the noise. The noise attenuation within the air cleaner filter, however, has been regarded as negligible by the field engineers. In this paper, for the analysis of the acoustical performance of air filter, an acoustical model was suggested and the characteristics of air filter system were investigated. Fibrous structure of the filter element was modeled as a micro-perforated panel using the flow resistivity and porosity. The pleated geometry of the filter element was modeled as two coupled ducts that have permeable walls, in which each duct area was assumed being constant. Using such simplified geometry, a mathematical model was developed for the sound propagation within a narrow duct system. Visco-thermal effect was considered in modeling the sound propagation through such tubes; the filter box was modeled as a rigid rectangular box. By combining two models, a four-pole transfer matrix was derived. For the validation purpose, transmission loss was measured for a plastic rectangular box containing an air filter. A noticeable effect of the air filter element was observed by including the filter into the box. Comparing the predicted and measured data, we found that the predicted TL agrees well with experimental results, in particular, in magnitude and frequency at TL troughs.

• Preventive Nutrition and Food Science
• /
• 제20권1호
• /
• pp.60-66
• /
• 2015

The aim of this study was to determine the heat-penetration characteristics using stationary and rotary retorts to manufacture Kimchi soup. Both heat-penetration tests and computer simulation based on mathematical modeling were performed. The sterility was measured at five different positions in the pouch. The results revealed only a small deviation of $F_0$ among the different positions, and the rate of heat transfer was increased by rotation of the retort. The thermal processing of retort-pouched Kimchi soup was analyzed mathematically using a finite-element model, and optimum models for predicting the time course of the temperature and $F_0$ were developed. The mathematical models could accurately predict the actual heat penetration of retort-pouched Kimchi soup. The average deviation of the temperature between the experimental and mathematical predicted model was 2.46% ($R^2=0.975$). The changes in nodal temperature and $F_0$ caused by microbial inactivation in the finite-element model predicted using the NISA program were very similar to that of the experimental data of for the retorted Kimchi soup during sterilization with rotary retorts. The correlation coefficient between the simulation using the NISA program and the experimental data was very high, at 99%.