# A Novel Predictable Rock Breaker Using Intelligent Hydraulic Control with ICT Convergences
## 3 Performance Evaluation and Field Test  
To validate the performance of the cascade control system, a flow meter and pressure sensor were installed to measure the impact frequency, energy, and efficiency. Experiments and a field test were performed at the Korea Institute of Machinery and Materials (KIMM). An adequate field test was operated manually to determine the result of each stroke. The impact frequency was calculated by inversing five consecutive operating cycle times, as in Equation (1). The impact energy (\(E_{i}\)) computed in Equation (2) from the wave over25 operating cycles with constant speed was shown to have pulse shape definiteness with no interference from other data. \[f_{i}=\frac{5}{t_{i}}, \tag{1}\]  
\[E_{i}=\frac{CF^{2}}{A_{t}\cdot\sqrt{E_{t}\cdot\rho_{t}}}\cdot\int_{t_{i}}^{t_{ n}}{\varepsilon_{i}}^{2}\cdot dt, \tag{2}\]  
\[\varepsilon_{i}=\frac{4\cdot U}{2.6\cdot k\cdot U_{B}\cdot K_{a}}, \tag{3}\]  
\[\eta_{tot}=\frac{E_{i}\cdot f_{i}}{Q\cdot(P_{s}-P_{r})}, \tag{4}\]  
The deformation \(\varepsilon_{i}\) measured the initial to final operation time from the selected wave, excepting preloading time of equipment, using the arithmetic mean as shown in Equation (3). The specifications of the products used in the experiment are listed in Table 3. The experimental conditions included an environmental temperature of \(22\pm 10\)\({}^{\circ}\)C and \(50\pm 30\%\) relative humidity. The variables of the equations are listed in Table 4, including the units. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Strength (MPa)** & **Weather-ed** & **Soft** & **Medium Hard** & **Hard** & **Extremely Hard** \\ \hline Construction Association of Korea & 30 & 70 & 100 & 130 & 160 \\  & \(\sim\) & \(\sim\) & \(\sim\) & \(\sim\) & \(\sim\) \\  & 70 & 100 & 130 & 160 & \\ \hline Korea engineering and consulting & \(\sim\) & 5 & 30 & 80 & \\ association & 5 & \(\sim\) & \(\sim\) & \(\sim\) & \(\sim\) \\  & 30 & 80 & 150 & \\ \hline Korea Expressway Corporation & \(\sim\) & 60 & 80 & 100 & \\  & 60 & \(\sim\) & \(\sim\) & \(\sim\) & - \\  & & 80 & 100 & & \\ \hline Seoul Metro & \(\sim\) & 10 & 25 & 50 & 100 \\  & 10 & \(\sim\) & \(\sim\) & \(\sim\) & \(\sim\) \\  & 25 & 50 & 100 & & \\ \hline Korea Train Express & \(\sim\) & 5 & 25 & 50 & 100 \\  & 5 & \(\sim\) & \(\sim\) & \(\sim\) & \(\sim\) \\  & 25 & 50 & 100 & & \\ \hline Seoul Metropolitan Government & \(\sim\) & 10 & 25 & 50 & 100 \\  & 10 & \(\sim\) & \(\sim\) & \(\sim\) & \(\sim\) \\  & 25 & 50 & 100 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Criteria of the rock according to uniaxial compressive strength. A field test was carried out to confirm the possibility of applying this system in conventional heavy industries, as shown in Figure 9. Attached to the system were the pressure sensor, flow rate sensor, temperature meter, and strain gauge. The actual experiment evaluated the performance of the hydraulic breaker in long and short stroke modes. Figure 10 shows the impact frequencies. While in the long stroke mode, there were five impacts in 1.2-2.2 s. In the short stroke mode, there were four impacts in 1.5-2 s. Using the strain gauge composed of a Wheatstone bridge, and the measured voltage value is converted into impact energy through Equations (2) and (3), as shown in Figure 11.