나무의 kinetic parameter 최적화 연구

박원희(Won-Hee Park) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

Activation energy of the flooring of a wood specimen is obtained by using thermogravimetric analysis. Two methods, Friedman and Flynn-Wall-Ozawa methods are adopted to obtain activation energy. The proposed mechanism is the three steps mechanism. Kinetic parameters such as activation energies, pre-exponential factors and reaction orders of the three steps mechanism are obtained by using repulsive particle swarm optimization.

표면의 대류열전달계수, 방사율 및 화염 열유속 역해석 연구

윤경범,박원희 한국화재소방학회 2013 한국화재소방학회논문지 Vol.27 No.6

반발 입자 군집 최적화 알고리즘을 이용하여 시편 표면에서의 대류열전달 계수, 방사율 및 화염에 의한 열유속을 예측하였다. 콘 칼로리미터를 이용하여 여러 열유속 조건 하에서의 방무목 시편의 표면 온도와 질량감소율 및 발화시간을 측정하였다. 본 연구에서 최적화된 대류열전달계수, 방사율 및 화염에 의한 열유속을 이용하여 계산된 표면온도는 실험결과와 각 열유속에 대하여 평균오차가 2% 내로 잘 일치하였다. 본 연구에서 제시한 방법을 이용하여 실험적 방법으로직접 측정하기 매우 어려운 화염이 발생하는 표면에서 열전달과 관련된 여러 물리량을 구할 수 있다. The convective heat transfer coefficient, emissivity, and flame heat flux on the surface of Duglas fir are estimated by using repulsive particle swarm optimization. The surface temperature, mass loss rate, and ignition time are measured for various incident heat fluxes from a cone heater of the cone calorimeter. The calculated surface temperatures obtained by using the optimized convective heat transfer coefficient, emissivity and flame heat flux on the surface in this study match well with those obtained from the test. The maximum error between the predicted and measured surface temperatures for the three different external heat fluxes is within 2% showing reasonable agreements. The methodology proposed in this study can be used to obtain various values related to heat transfer on a flaming surface that are difficult to measure in experiments.

Optimization of fire-related properties in layered structures

박원희 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.8

In present paper, fire-related properties of materials with multilayered structure are obtained through reverse heat transfer analysis. For this purpose, one-dimensional heat transfer equation including pyrolysis is analyzed to simulate the fire phenomenon of multi-layered solid materials. The fire-related properties can be obtained by optimizing the objective function expressing the difference between the measured values and the results (surface temperature and mass loss rate under constant incident heat flux) obtained by analyzing the considered heat transfer equations. Repulsive particle swarm optimization is used as the optimization technique. The optimized properties of single-, two- and three-layered materials obtained with the assumed properties were compared to the assumed for various incident heat fluxes. Using a cone calorimeter, the surface temperature and mass loss rate were measured over time with three constant heat fluxes applied to three layers of sandwich type material. The fire-related properties of each layer of the sandwich type material were calculated using the measured results. The technique considered in this study can be applied for determining the fire characteristics of multilayered materials is suitable for engineering the necessary properties to predict fire propagation in solid material.

Estimation of pyrolysis-related properties using repulsive particle swarm optimization

박원희,Kyung-Beom Yoon,Hee-Chul Chang,김태국 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.7

The pyrolysis-related properties of the specimen are obtained by optimizing the repulsive particle swarm optimization technique. Eight pyrolysis-related properties were obtained: virgin thermal conductivity, char thermal conductivity, virgin specific heat, char specific heat,char density, heat of pyrolysis, pre-exponential factor, and activation energy. The surface temperature and the mass loss rate obtained using the optimized properties were consistent with the measured values. In assuming that the properties obtained are physically valid,and that the surface temperature and mass loss rate measured in the experiment are correct, a valid fire phenomenon may be considered for replication if fire analysis is conducted using the properties obtained from the procedures proposed in this study.

Application of repulsive particle swarm optimization for inverse heat conduction problem – Parameter estimations of unknown plane heat source

Elsevier 2019 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.137 No.-

<P><B>Abstract</B></P> <P>The major objective of the present study is to demonstrate the performance and efficiency of the Repulsive Particle Swarm Optimization (RPSO) method as an inverse analysis solver by extending its application to the inverse heat conduction problem. As the first outcome, an estimation of unknown parameters of a time-varying plane heat source in a one-dimensional inverse heat conduction problem was considered. The overall performance of the RPSO method was examined based on the effects of the forms of unknown heat source, the number of parameters, the measurement errors and the population sizes on the estimation accuracy. In addition, the final results were compared with those of the Levenberg-Marquardt Method (LMM), which is widely used for the inverse heat conduction problem, to investigate the advantages and disadvantages of the RPSO method.</P> <P>The present results prove that the RPSO method has more robust characteristics and yields rather confidential inverse estimations than the LMM for the inverse heat conduction problem although it requires more computational cost.</P> <P><B>Highlights</B></P> <P> <UL> <LI> RPSO method extended its application to the inverse heat conduction problem. </LI> <LI> Considered the parameter estimation approach of unknown time-varying plane heat source. </LI> <LI> Results of RPSO were compared with the Levenberg-Marquardt method (LMM). </LI> <LI> RPSO showed accurate and robust performance for various types of heat sources. </LI> <LI> RPSO can be an efficient inverse solver for the inverse heat conduction problem. </LI> </UL> </P>

확산지배 난류 연소현상에서 역해석을 이용한 CH₄/O₂의 초기 질량분율 추정에 관한 연구

이균호(Kyun Ho Lee),백승욱(Seung Wook Baek) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.7

본 연구에서는 기존의 역열전달 문제 (inverse heat transfer problem)와 같이 역해석 (inverse analysis)을 통해 미지의 파라미터를 추정(estimation)하는 개념을 복잡한 연소문제에 도입하였다. 기존의 연구에서는 역해석 기법을 연소문제 자체에 보다는 대부분 연소현상을 동반한 복사열전달과 같은 역열전달 문제에 국한해서 적용하고 있기 때문에, 열전달 문제에 한정되어 사용되고 있는 기존의 역해석을 새로운 공학문제에 확장하여 적용함과 동시에 효율적인 연소기 설계 및 최적화 개념을 제시하는데 본 연구의 의의가 있다고 할 수 있다. 이를 위해 실제적으로 많이 사용하고 있는 축대칭 원통형 연소기 내부로 주입되는 메탄(CH₄)과 산소 (O₂) 성분의 초기 질량분율 값을 연소기 입구 근방에서 측정한 개스의 온도 데이터를 이용하여 역추정하였다. 이때, 복잡한 확산지배 연소 현상을 효율적으로 역해석하기 위해 최적화 방법 중의 하나인 반발 입자 군집 최적화 방법을 역해석 기법으로 적용하였다. The major objective of the present study is to extend the applications of inverse analysis to more realistic engineering fields with a complex combustion process rather than the traditional simple heat-transfer problems. In order to do this, the unknown initial mass fractions of CH₄/O₂ are estimated from the temperature measurement data by inverse analysis in the practical diffusion-controlled turbulent combustion problem. In order to ensure efficient inverse analysis, the repulsive particle swarm optimization (RPSO) method, which belongs to the class of stochastic evolutionary global optimization methods, is implemented as an inverse solver. Based on this study, it is expected that useful information can be obtained when inverse analysis is used in the diagnosis, design, or optimization of real combustion systems involving unknown parameters.

Inverse estimation of various surface emissivity distributions using repulsive particle swarm optimization

Elsevier 2019 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.134 No.-

<P><B>Abstract</B></P> <P>The aim of the present study is to demonstrate further inverse solving capability of the repulsive particle swarm optimization (RPSO) method by estimating unknown surface radiative property of various distributions in a surface radiation problem. A distribution of the surface emissivity was selected as the unknown property to retrieve and was defined as arbitrary functional forms to simulate various profiles in an axisymmetric cylindrical enclosure with nonparticipating media condition. A total of four functional forms were examined with uniform, rectangular step, triangular ramp and polynomial curve profiles. Also, the number of unknowns was increased to verify if the RPSO method could still retrieve property values exactly when compared with a previous study. In conclusion, the present results proved that the RPSO method showed accurate and robust performance as the inverse solver due to a superior search capability for the inverse surface radiation problem involving numerous unknown parameters of various distributions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Unknown surface emissivity distributions of various forms were estimated by RPSO. </LI> <LI> RPSO showed accurate and robust performance for various emissivity distributions. </LI> <LI> RPSO can be an efficient inverse solver for the inverse surface radiation problem. </LI> </UL> </P>

RPSO 알고리즘을 이용한 벽면 방사율 추정에 관한 연구

이균호(Kyun Ho Lee),백승욱(Seung Wook Baek),김기완(Ki Wan Kim),김만영(Man Young Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

An inverse radiation analysis is presented for the estimation of the wall emissivities for an absorbing, emitting, and scattering media with diffusely emitting and reflecting opaque boundaries. In this study, a repulsive particle swarm optimization(RPSO) algorithm which is a relatively recent heuristic search method is proposed as an effective method for improving the search efficiency for unknown parameters. To verify the performance of the proposed RPSO algorithm, it is compared with a basic particle swarm optimization(PSO) algorithm and a hybrid genetic algorithm(HGA) for the inverse radiation problem with estimating the wall emissivities in a two-dimensional irregular medium when the measured temperatures are given at only four data positions. A finite-volume method is applied to solve the radiative transfer equation of a direct problem to obtain measured temperatures.

난류확산 연소 현상에서 역해석을 이용한 메탄/산소의 초기 질량분율 추정에 관한 연구

이균호(Kyun-Ho Lee),백승욱(Seung-Wook Baek),한상헌(Sang-Heon Han) 한국연소학회 2008 KOSCOSYMPOSIUM논문집 Vol.- No.-

The major objective of the present study is to extend the applications of an inverse analysis from traditional heat transfer problems to new area which involves more complex combustion problems. To do this, unknown initial mass fractions of fuel/oxidizer, are estimated from measurement data by inverse analysis in the practical turbulent diffusion combustion problem. For efficient analysis, the present repulsive particle swarm optimization(RPSO) method is implemented as an inverse solver because the prediction of combustion phenomena of such systems is rather complex than traditional inverse heat problem. Therefore, it is meaningful in that useful information can be obtained by inverse analysis when it is applied to diagnosis, design or optimization of the real combustion systems involving unknown parameters.

축대칭 원통형 연소기로 공급되는 메탄/산소의 유입속도 역추정에 관한 연구

이균호(Kyun Ho Lee),백승욱(Seung Wook Baek) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5

본 연구에서는 기존의 역열전달 문제(Inverse Heat Transfer Problem)와 같이 역해석(Inverse Analysis)을 통해 미지의 파라미터를 추정(Estimation)하는 개념을 복잡한 연소문제에 도입하였다. 이를 통해 궁극적으로 열전달 문제에 한정되어 사용되고 있는 역해석을 새로운 공학문제에 확장하여 적용함과 동시에 효율적인 연소기 설계 및 최적화 개념을 제시하고자 하는 것이 목적이다. 본 연구를 위해 실제적으로 많이 사용하고 있는 축대칭 원통형 연소기 내부로 공급되는 메탄(CH₄)과 산소(O₂) 성분의 초기 유입속도를 연소기 입구 근방에서 측정한 개스의 온도 데이터를 이용하여 역추정하였다. 이 때, 복잡한 확산지배 연소 헌상을 효율적으로 역해석하기 위해 최적화 방법 중의 하나인 반발 입자 군집 최적화(Repulsive Particle Swarm Optimization, RPSO) 방법을 역해석 기법으로 적용하였다. The major objective of the present study is to extend the applications of an inverse analysis to more realistic engineering area with a complex combustion process than traditional simple heat transfer problems. In order to do this, unknown inlet velocities of methane/oxygen are estimated from measurement data using inverse analysis in the practical diffusion-controlled turbulent combustion problem. For efficient inverse analysis, the repulsive particle swarm optimization method is implemented as an inverse solver.