## 1 Introduction
The thermal conductivity and length for BHE in one place should be the same in continuous testing, whereby only BHE type and grouting material can be changed. Ground thermal conductivity (I) and thermal resistance (Rb) for different coaxial BHE types and grouting materials were obtained. To the best of the authors' knowledge, field studies of this combination are yet to be conducted in the literature. The effectiveness of thermal bore hole resistance was evaluated against the GSHP's coefficient of performance (COP) and could not be ignored. The previous study's standing column well (SCW) [20; 21] showed that the SCW can reduce the overall borehole length compared to a conventional closed-loop system consisting of a single U-tube heat exchanger. In addition, the improvement of the performance of the SCW can be improved by utilizing groundwater, and some groundwater from the well is discharged (exhausted) without being completely recycled to the SCW system. Groundwater bleeding regulates the well temperature by inducing a flow toward the well. [PERSON] et al. 's [22] parametric research showed that bleeding rate is one of the most important parameters affecting SCW performance, and integrating a bleeding strategy into SCW can significantly reduce depth, capital cost, and life-cycle cost compared to no bleeding. Numerical studies of previous models of standing column wells [23; 24; 25] made many assumptions about heat transfer between the various components of the well. There are relatively few design tools and simulation models available for SCW systems [26; 27; 22]. Standing column wells are in limited use since the development of geothermal heat pump systems; however, in recent years, overall performance improved in areas with adequate hydrological and geological conditions, attracting more attention [28; 29; 30; 22]. In addition, many studies using single- and multi-well standing column wells were carried out recently, and studies reported that the efficiency is improved by using a plurality of SCW systems and using bleeding of water rather than a sealed heat exchanger. In recent years, SCW systems, which are more efficient than sealed type, are increasingly installed in areas where geological properties and groundwater utilization conditions are suitable [31; 32]. The focus of attention on these systems is not only due to the high thermal efficiency of the SCW system, but also because the SCW system requires less construction area than the enclosed system, which is of primary importance in urban areas. In the case of the SCW system, a numerical analysis model is being developed by applying finite volume and finite element methods in consideration of complex underground heat and groundwater circulation [33; 34; 35; 36]. However, these numerical models cannot be reflected in hourly simulation programs or designs because calculations are too complicated and conditions over time are too heavy. Therefore, it is often simplified by an empirical approach and approximation from real design. This is why the direction and performance of recent research focused on the development of models that simplify the SCW system [37; 38; 39]. The groundwater heat pump system using groundwater extracted from the same well hole and being recovered into the same well hole in a semi-open loop arrangement was widely known as the SCW (standing column well) system. The ground heat exchangers in these systems consist of vertical boreholes filled with groundwater up to the groundwater level [40; 41]. In an open-loop pipe circuit, water is circulated from the well through a heat pump to return to the same well, and, for most of the year, the system works by recirculating water between the well and the heat pump. However, during the peak temperature period, only a portion of the flow can be returned to the well, and the rest can be drained to \"bleed\" some water from the system [41]. This leads to groundwater flow from the surrounding formation to the well.