## 1 Introduction
The forecast accuracy of the physical model can quickly decrease with the number of input variables unless their values are properly forecast. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Reference**} & \multirow{2}{*}{**Year**} & \multirow{2}{*}{**Area**} & \multicolumn{2}{c}{ \begin{tabular}{c} **Koppen Climate** \\ **Classification** \\ **(Subtype)** \\ \end{tabular}  } & \multirow{2}{*}{**Model**} & \multirow{2}{*}{**RMSE (W/m\({}^{2}\))**} & \multirow{2}{*}{**rRMSE (\%)**} & \multirow{2}{*}{\ \begin{tabular}{c} **Satellite** \\ **System** \\ \end{tabular}  } \\ \hline \multirow{2}{*}{[PERSON] et al. [10]} & \multirow{2}{*}{1996} & \multirow{2}{*}{Germany} & \begin{tabular}{c} Continental (Dfc) \\ Teparete (Cfa, Cfb) \\ \end{tabular}  & Semi-empirical & \(-\) & 16 & Meteosat-1 \\ \hline \multirow{4}{*}{[PERSON] et al. [2]} & \multirow{4}{*}{2002} & \multirow{4}{*}{United States} & Dry (All subtypes) & \multirow{4}{*}{118} & \multirow{4}{*}{\(-\)} & \multirow{4}{*}{GOES} \\  & & & & & & & \\ \cline{1-1}  & & & & & & & \\ \cline{1-1}  & & & & & & & \\ \cline{1-1}  & & & & & & & \\ \cline{1-1}  & & & & & & & \\ \cline{1-1}  & & & & & & & & \\ \cline{1-1}  & & & & & & & & \\ \hline \multirow{4}{*}{[PERSON] et al. [8]} & \multirow{4}{*}{2003} & \multirow{4}{*}{Europe} & Dry (Bsk, BWh) & \multirow{4}{*}{Semi-empirical} & \multirow{4}{*}{\(-\)} & 35 & \multirow{4}{*}{Meteosat-2} \\  & & & & & & & (1 h ahead) \\ \cline{1-1}  & & & & & & 40 \\ \cline{1-1}  & & & & & (2 h ahead) & \\ \hline \multirow{4}{*}{[PERSON] et al. [3]} & \multirow{4}{*}{2004} & \multirow{4}{*}{Europe} & Dry (Bsk, BWh) & \multirow{4}{*}{Semi-empirical} & \multirow{4}{*}{\(-\)} & 45 (Jan 95) & \multirow{4}{*}{Meteosat-1} \\  & & & & & & 27 (Apr 95) & \multirow{4}{*}{Meteosat-1} \\  & & & & & & 18 (Jul 94) & \\ \cline{1-1} \cline{4-1}  & & & & & & & \\ \cline{1-1} \cline{4-1}  & & & & & & & \\ \cline{1-1} \cline{4-1}  & & & & & & & \\ \hline \multirow{4}{*}{[PERSON] et al. [12]} & \multirow{4}{*}{2012} & United Arab & \multirow{4}{*}{Dry (Bwh)} & Semi-empirical & 123 & 18.3 & Meteosat-2 \\ \cline{1-1}  & & & & & & & \\ \cline{1-1} \cline{4-1}  & & &  
[PERSON] et al. [9] proposed a pioneering form of the semi-empirical model, known as the Heliosat-1 model, which has become a fundamental technique for numerous following models. They assumed that the cloud index (CI) can be estimated based on the brightness of satellite sensor data. They calculated GHI by simply reducing clear-sky GHI according to the CI. Since then, [PERSON] et al. [3], [PERSON] et al. [2], [PERSON] et al. [8], [PERSON] et al. [10], and other scholars made improvements on the [PERSON] model. As the well-known semi-empirical models were mainly developed using data in Europe and North America, many researchers evaluated and modified them for application to various other regions [6; 11; 12]. Table 1 implies that, based on Koppen-Geiger climate classification [24; 25], the semi-empirical models were mostly dedicated to continental and temperate areas. Only a few studies addressed a hot summer continental climate, which is categorized as the \"Dwa\" subtype. In the northern region of China, [PERSON] et al. [4] predicted GHI 1, 2, and 3 h ahead by using particle image velocimetry and the Rigollier method. [PERSON] et al. [16] combined the McClear clear-sky irradiance [18] and Rigollier models to estimate GHI at Zhangbei. Both the studies utilized the Fengyun-4 satellite system. In Korea, several studies have attempted to extract GHI from Korea's Communication, Ocean, and Meteorological Satellite (COMS) system [15; 17; 19; 22; 23]. Since the COMS system was developed, most studies have focused on physical models. [PERSON] et al. [19] initiated GHI modeling by using COMS data as input and introducing a physical model, which is called the Gangneung-Wonju National University (GWNU) model. [PERSON] et al. [22] applied the Kawamura model [26] and generated a solar irradiance map by considering topographical factors, such as terrain slope. In addition, [PERSON] et al.