• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.469-476
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• 2001

The Ν-value in the standard penetration test(SPT) is affected by the magnitude of the rod penetration energy transmitted from the falling hammer as well as the geotechnical characteristics of the ground. Understanding of the striking energy efficiency in the SPT equipment is getting important for that reason. The energy efficiencies of the doughnut hammer with the hydraulic lift system and the automatic trip hammer system were investigated through field tests using the instrumented rod and wave-signal acquisition systems including the pile driving analyzer(PDA) . The rod energy ratio, ΕR$\_$r/ was defined as the ratio of the energy delivered to the drilling rod to the potential free-fall energy of the hammer. It appears that the type of the hammer and lift/drop system had a strong influence on the energy transfer mechanism and ΕR$\_$r/ also varies according to the energy instrumentation system and the analysis methods.

• Journal of the Korean Geotechnical Society
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• v.21 no.9
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• pp.5-12
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• 2005

SPT hammer energy and its delivery are hon to influence the N value. The SPT hammer energy is classified into theoretical energy, velocity energy, rod energy and dynamic efficiency. In this study, the rod energy and the velocity energy are measured directly by PDA and Digital Line-Scan Camera which are most widely used type of SPT apparatus in Korea. The Dynamic efficiency is calculated through measured data. As the results of this study, the averages of rod energy ratio of donut, safety and automatic hammer are measured at 49.57, 61.60, and at $87.04\%$ by FV method. The averages of hammer velocity of donut, safety and automatic hammer are measured at $3.177{\pm}0.872$, $3.385{\pm}0.681$, and at $3.651{\pm}0.550$ m/s by Digital Line-Scan Camera, with the dynamic efficiencies at 0.732, 0.801, and 0.973 respectively.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.71-78
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• 2002

The N-value from the standard penetration test(SPT) is affected by the magnitude of the rod penetration energy transmitted from the falling hammer as well as the geotechnical characteristics of the ground. Understanding of the striking energy efficiency in the SPT equipment is getting important for that reason. The energy efficiencies of the various type of equipment were investigated through field tests using the instrumented rod and wave-signal acquisition systems including the pile driving analyzer(PDA). The rod energy ratio, ERr was defined as the ratio of the energy delivered to the drilling rod to the potential free-fall energy of the hammer. It appears that the type of the hammer and lift/drop system had a strong influence on the energy transfer mechanism and ERr also varies according to the energy instrumentation system and the analysis methods.

• New & Renewable Energy
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• v.4 no.2
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• pp.31-38
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• 2008

Using a surplus head in presented water supply pipes, we have studied to improve the operating efficiency of small hydro generator, which was chosen for a test model with 00 hydro power plant. With regard to power control and countermeasure of water hammer impact, Finally we have represented the optimal control method through the synthetical analysis of existing system symptoms, operation efficiency, the effect of water hammer impact and system configuration.

• Journal of the Korean Geotechnical Society
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• v.22 no.12
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• pp.33-43
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• 2006

Driving tests using model plastic piles with different hammer cushion materials were performed in order to evaluate the efficiency of energy transfer ratio from the hammer, degree of vibration of the surrounding ground and noise due to impacting. A small pile driving analyzer (PDA) was composed using straingages and Hopkinson bar which is measuring force signal and pile-head velocity. The hammer cushion (cap block) materials used for the model driving tests were commercial Micarta, plywood, polyurethane, rubber (SBR) and silicone rubber. The highest energy transfer ratio was obtained from Micarta in the same soil and driving conditions. Micarta was followed by polyurethane, plywood, rubber and silicone in descending order. The more efficient energy transfdr ratio of the hammer cushion materials became, the bigger average noisy (sound) level was found. In addition, Micarta and polyurethane provided bigger bearing capacities than other materials compared in the same soil and driving conditions in which the static loading tests were performed at the end of driving.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.338-341
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• 2009

In this paper, three-dimensional finite element approach to determining the number of blows in hammer forging is presented. Energy efficiency which is a major factor affecting the number of blows in hammer forging is assumed to decrease linearly as die-material contact area increases. The approach is applied to predicting the number of blows in counterblow hammer forging of large crank shaft for medium sized ship engine.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.28-35
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• 2004

Driven pile has the excellent bearing characteristics and good economics, so it is known as the comparative piling method. To use the advantages of driven pile fully, it is necessary to perform the proper construction management. Engineers must drive pile to the proper bearing layer with proper blow energy and measure the blow count and penetration per certain depth to analyze the bearing capacity and driveability. In conventional method, these parameters have been measured manually so it was difficult to get good accuracy. After PIR-D(Pile Installation Recorder-Driven Pile) was attached to the driving equipment, the hammer efficiency, blow count and penetration in blow/10cm were measured automatically. In this paper, to givethe rational judgement criteria of bearing layer, driveability, blow/10cm according to pile depth during pile driving, the some relationship between the driving resistance and ground layer distribution was analyzed. The ground investigation during piles (PHC ${\Phi}450,\;{\Phi}400\;&\;Steel\;Pile\;{\Phi}609{\ast}16t$) installation in the marine clay layer in Incheon, the sandy soil layer in Yongin and the tuff layer in Pusan was done. And measuring hammer efficiency not doing recently, we could compare hammer efficiency(Eh) by PIR-D and energy transfer ratio(ETR) by Pile Dynamic Analyzer(PDA).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.6
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• pp.603-611
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• 2016

Research and development of mineral-resource-related products has progressed with the increased need to develop mineral resources. The DTH hammer is a resultant product. However, owing to particular work conditions of underground drilling, it is difficult to obtain direct data on the DTH hammer. A DTH drill rig requires a significant amount of money and time for actual testing. This thesis aimed to resolve this problem by using CAE. In a previous paper, the structure of the DTH hammer and its movement were analyzed, and a standard model based on simulation was proposed. Then, experimentation and comparison verification were conducted. In this paper, by using an experimental design method, we derived a control factor of the impact force and efficiency of the DTH hammer and attempted to optimize the design. As a result, the impact energy increased by 14.9%, and the efficiency increased by 3.3%.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1425-1434
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• 2009

This study was aimed at comparing and assessing SPT-N values both measured by automatic and manual record devices of Standard Penetration Test. As a result, energy efficiency of hammer was approximately 62.9%, meaning SPT-N value measured by automatic recording device showed relatively accurate performance that the one done by manual device. Given the relations between hit frequency of automatic recording device and intrusion, the characteristics of stratum are expected to be proved in more accurate way. Additionally, higher confidence level seems to make it preferred and quality assessment method.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.126-129
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• 2008

Using a surplus head in presented water supply pipes, we have studied to improve the operating efficiency of small hydro generator, which was chosen for a test model with Sung-Nam and Bo-Ryong small hydro power plant. With regard to power control and countermeasure of water hammer impact, Finally we have represented the optimal control method through the synthetical analysis of existing system symptoms, operation efficiency, the effect of water hammer impact and system configuration.