• Current Research on Agriculture and Life Sciences
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• v.1
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• pp.95-100
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• 1983

A soil hardness meter with strain gages was developed in order to measure the hardness of the soil. Soil hardness tests were conducted at the laboratory based on this measuring system. Also, these results were compard with that from the cone penetrometer which is widely used for this purpose. The following conclusions were drawn from the results. 1. Since the correlation coefficient of calibration curve obtained from the soil hardness meter with strain gages was 0.99876 and that of calibration curve obtained from the cone penetrometer with dial gage was 0.97150, the soil hardness meter with strain gages was more recomendable than that with dial gage for this purpose. 2. Standard deviations of soil hardness for sands and soil of paddy field when the soil hardness meter with strain gages was used were 6.794 and 8.271, respectively and that of soil hardness for sands and soil of paddy field when the cone penetrometer with dial gage was used were 7.490 and 9.169, respectively. Thus, the soil hardness meter with strain gages seemed to have lower measuring error than with dial gage.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.5
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• pp.126-132
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• 2002

Misaligned shafts of the rotating machinery have caused noise, vibration. bearing failures, and stress concentration of coupling parts which decrease the efficiency and life of shaft systems. Therefore the proper shaft alignment of those system should be monitored continuously in dynamic condition. To solve these problems under dynamic condition a telemetry system is used. In this study, the condition of the least bending moment which is known by analyzing the structure and stress induced by misalignment is found. After the shaft is aligned by dial gage, a telemetry system with strain gages is installed on shaft. The relationship between bearing displacement and moment of coupling part influenced by misalignment is investigated. The moment derived from two shaft strain at the nearby coupling is measured. The bending strain is measured 5 times for average in static state as well as in dynamic state with 100∼700 rpm.

• Journal of Power System Engineering
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• v.13 no.3
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• pp.40-46
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• 2009

This study on the bolt elongation and torque measuring method by ultrasonic nod-destructive method. In the past, The dial gage was used for the elongation measurement of gas turbine bolts. The purpose of this study is to improve the traditional bolt elongation measurement method. The old method using dial gage measures the elongation of the gas turbine bolt. If the length differences among the loading bolts are within the required range, The loading torques of bolts consider as acceptable. But this method can not give the information about torque differences among the loading bolts. It could bring out vibration of turbine due to loading torque differences among the bolts. So the elongation and torque must be measured simultaneously. The new technology using ultrasonic non-destructive method can give the information about bolt elongation and torque. The ultrasonic method basically measures the speed in the bolt material for the calculation the bolt elongation. But the ultrasonic speed varies according to temperature and loading torque of bolts. So the factors of temperature and loading power were investigated and reflected to the calculation of bolt elongation and torque. The results of this study shows the big difference among the bolts torque in the old method and the torque differences among the bolts can be adjusted by reflecting the result of this study. And this torque adjusting method can decrease gas turbine vibration problem due to torque difference among the bolts. So this paper shows ultrasonic method is better than old method for the measurement of bolt elongation and torque.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.63-68
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• 1999

Because misaligned shafts have caused noise, vibration, bearing failures, and stress concentration of coupling part, which decrease the efficiency and life of a shaft system, the proper alignment of shaft system should be monitored continuously in dynamic condition. To solve these problems under dynamic condition, a telemetry system is this study is used to find the condition of the least bending moment, which is known by analyzing the structure and stress induced by misalignment is investigated. The moment derived from two shaft strain at the nearby coupling is measured. The bending strain is measured 5 times for average in static state as well as dynamic state with 100~700 rpm.

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.79-79
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• 1999

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.517-522
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• 2000

In the past few years, the nondestructive inspection technology has greatly developed due to the increased necessity to gain a complete understanding of the bridge behavior. Especially, the deformations of bridges contain a lot of informations about its health state. By measuring these deformations it is possible to analyze the loading and aging behavior of the structure. However, the current methods (such as LVDT, dial gage, optical displacement tranceducer, etc) are often of changeable application on site and have the limitations of installation. In this paper, the classical beam theory was reviewed and the deflections of structure are estimated using measured strain which is easy to acquire. The applicability of this algorithm is verified by a preliminary steel beam test and two types of concrete beam tests. Also fiber optic sensors as well as resistive strain gages were installed in the concrete beams to establish the applicability of fiber optic sensors in the field of civil engineering.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.859-866
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• 2001

During the Pre-service Inspection for Wolsong Unit 3&4 in 1997/1998 respectively, 17 Distorted Roll Transition indications(over expanded beyond tubesheet secondary face) were identified at the Unit 4 (S/G B, D). Six(6) tubes out of these tubes were plugged in 1998. However the first Periodic Inspection identified additional 110 indications in 1999 and 2000. The additionally identified 110 indication call, not reported at the Pre-service Inspection, are; 2 Not-Finally-Expanded-Tubes and 108 Distorted Roll Transition tubes. Design limit of each Steam Generator tube Plugging is 6.4%. Plugging was performed by the Steam Generator manufacturer under the warranty. When Distorted Roll Transition indications were first identified on the Unit 4 in 1998 the degree of Over-expansion was measured using an inner dial-gage to make the disposition of Nonconformance report. 2 Not-Finally-Expanded-Tubes were plugged and 10 tubes out of 108 Distorted Roll Transition Tubes were also plugged as a preventive measure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.3
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• pp.173-180
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• 2001

In the past few years, the nondestructive inspection technology has greatly developed due to the increased necessity to gain a complete understanding of the bridge behavior. Especially, the deformations of bridges contain a lot of informations about its health state. By measuring these deformations it is possible to analyze the loading and aging behavior of the structure. However, the current, methods (such as LVDT, dial gage, optical displacement transducer, etc) are often of changeable application on site and have the limitations of installation. In this paper, the classical beam theory was reviewed and the deflections of structure are estimated using measured strain which is easy to acquire. The applicability of this algorithm is verified by laboratory(simple reinforced concrete beam) and field test. By this test, we proposed correction factor to estimate deflection of reinforced concrete beam after cracking, and analyze about the generation of correction factor. Also fiber optic sensors as well as resistive strain gages were installed in the concrete beams to establish the applicability of fiber optic sensors in the field of civil engineering.