## 1 Introduction  
Additive manufacturing (AM) is a manufacturing technology that builds a 3D structure from a digital model with a layer-by-layer sequence, and research to apply AM technology to the production of parts is being actively conducted worldwide. In particular, Laser Powder Bed Fusion (LPBF) using metal powder can easily produce parts with a precise and complex structure that cannot be manufactured with conventional manufacturing methods, and it is possible to reduce the weight of parts by topology optimization or lattice structures. Due to these advantages, the use of AM technology is increasing in various industry such as motor vehicles, aerospace, and medical/dental [1]. In order to use the AM manufactured part as an end-use product rather than a prototype in the industry, stability of the material and quality assurance must be guaranteed. For this, it is necessary to accurately predict the characteristics of parts with respect to powder properties and process parameters such as scan pattern, scan speed, and laser power. If the behavior and characteristics of parts can be predicted accurately by a high-fidelity simulation for the LPBF process, time-consuming and expensive specimen or prototype production and testing can be minimized. For the LPBF process simulation, sequentially coupled thermal-stress analysis is performed, since the stress and deformation fields are affected by the temperature field. Temperature history is obtained by thermal analysis, and residual stress and distortion are predicted by applying temperature history to stress analysis. Therefore, precise thermal analysis must be preceded to obtain accurate and reliable LPBF simulation results. In the LPBF process, metal powders experience a temperature change from room temperature to above the melting point by the laser heat source, so that phase change occurs. In the thermal analysis for the LPBF process simulation, an appropriate heat source model among various heat source models such as a surface Gaussian heat source, a volumetric Gaussian heat source, and a cylindrical shape heat source [2; 3] is selected, and phase and temperature-dependent material thermal properties are applied to represent phase changes. Heat dissipation to the environment is considered as boundary conditions such as convection and radiation on the powder surface. However, the analysis parameters such as material properties or thermal coefficients that are used to describe the thermal analysis model for the LPBF process simulation are not only affected by temperature, phase, powder characteristic, etc. but also are difficult to measure accurately. In addition, thermal analysis is generally performed in mesoscopic scale by modeling powder as a continuum without considering in detail complex physical phenomena at the microscopic level such as heat transfer between powder particles, evaporative cooling, and molten metal flow, and this makes the determination of the proper values of analysis parameters more difficult. On the other hand, the effect of these analysis parameters on thermal analysis results such as temperature distribution and melt pool shape has not been fully understood or analyzed. Therefore, this situation leads to limited reliability and accuracy of thermal analysis for the LPBF process simulation. Many studies related to thermal analysis using FEM have been conducted to simulate the complex LPBF process accurately. [PERSON] et al. [2] performed fully coupled thermal-stress analysis considering multi-layer deposition of Ti-6 Al-4V in SLM (selective laser melting) to predict the melt pool shape and dimensions, and they experimentally validated the analysis results. Furthermore, the influence of process parameters and materials on the melting process was evaluated. [PERSON] et al. [3] performed thermal analysis applying eight heat source models to predict melt pool dimensions and surface features and compared the experimental results to select a suitable heat source model.