• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.6
• /
• pp.1099-1107
• /
• 1992

The apparent strain of temperature self-compensated strain gages at cryogenic temperature is presented. By joining the international round robin test on electrical strain gages at cryogenic temperatures, apparent strain curves of up to the fourth order with respect to the temperature are obtained with different strain gages and different materials. The liquid nitrogen and the liquid helium are employed to get the cryogenic environment. The results can be effectively utilized to determine the real strains by mechanical loading at cryogenic temperature. This paper also describes the optimal selection of strain gages and test materials for the use of strain gages at cryogenic temperature.

• Journal of the KSME
• /
• v.33 no.7
• /
• pp.661-670
• /
• 1993

스트레인 게이지를 이용한 응력측정 방법 및 응력 측정시의 오차 발생의 원인에 대해서 설명하 였고 현재 많이 사용되고있는 스트레인 게이지식 로드셀의 원리 및 구조에 대해서도 설명하였다. 스트레인 게이지를 이용하여 변형도를 측정할 경우 1% 이내의 정확도를 유지하는 것이 가능하나 측정된 변형도로부터 응력을 계산할 경우 재료상수들의 부정확성으로 인하여 5% 정도의 오차가 발생할 수 있다. 스트레인 게이지를 이용한 응력 측정값은 부착위치에서의 값이므로 구조물의 최대 응력을 측정하고자 할 경우 구조물의 응력 상태를 제대로 파악하지 못하면 큰 오차가 발 생할 수 잇다. 따라서 정확한 측정을 위해서는 정확한 게이지 작업 기술과 함께 하중에 대한 대상물의 거동을 파악하는 기술 습득이 요구된다. 스트레인 게이지식 로드셀을 직접 설계 및 제작하기 위해서는 용량, 정밀도, 설치 공간, 사용조건 등을 고려하여 감지부의 형상, 감지부의 재질, 스트레인 게이지의 종류, 부착 방법, 보상회로 구성방법, 보호 케이스의 부착 여부 등을 결정하여야 하고 제작이 완료된 후 힘 표준기 등으로 교정검사를 실시하여 사용하여야만 정확한 측정을 기대할 수 있다.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.1
• /
• pp.185-194
• /
• 2023

The 4-axis strain-gauge, which is widely applied to military weapon systems, is operated in poor temperature and vibration conditions, tolerance may increase and malfunctions may occur. To improve this, this paper proposes a signal-processing software technique for the tolerance of the 4-axis strain gauge applied to a military weapon system. First, the tolerance of the strain-gauge and the signal processing circuit according to the ambient temperature were evaluated and analyzed. Second, a software technique for processing the dead zone and offset area that can improve the tolerance of the strain-gauge is proposed. The experimental results applying the software technique confirmed that it operated normally in the temperature test and operation test. Therefore, the proposed software technique is valid and can be used as useful information to improve tolerance due to ambient temperature and vibration when designing a system using a strain-gauge.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.25 no.5
• /
• pp.384-390
• /
• 2005

In the numerical analysis of En (eddy current testing) using 3-dimensional FEM (finite element method), MVP (magnetic vector potential) and electric scalar potential are used as variables in conductor region. Three dimensional modeling makes number of unknowns increase, and the degree of freedom of variables also makes number of unknowns increase. Because of this reason, modified UP is used to reduce the number of unknowns. Gauge condition is enforced artificially on existing FEM formulations to insure the uniqueness of MVP. So in this paper the effects of these FEM formulation procedures on ECT are investigated and the appropriate FEM formulation is suggested for accurate ECT simulation.

• Journal of the Korea Concrete Institute
• /
• v.22 no.1
• /
• pp.85-91
• /
• 2010

In this study, the drying shrinkage strains were compared of 24~60 MPa concrete specimens subjected to various curing conditions and measurement methods were compared. And, the applicability of the test and prediction methods were investigated. According to the results, drying shrinkage was significantly reduced in 28 day curing condition. In the sealed curing case, drying shrinkage strain from demolding time was identical to the one of the standard curing case for low strength concrete, however, drying shrinkage strain was greatly increased than the standard case for high strength case because of the effect of autogenous shrinkage. The efficient measurement was possible using the embedded gage for concrete drying shrinkage, but, the measured value by contact gage was lower than the one by the embedded gage. The test results agreed with EC2 model better than the other.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.1
• /
• pp.38-44
• /
• 1996

The CAD system for design and drawing of limit gauges was constructed and developed. This system was made by Visual Basic program. Using this system, drawings together with concerned data for the manufacturing of limit gauges are generated on the screen, file and printer. The data base was constructed by referring handbooks, textbooks, relevant standards and regulations. This system was proved a powerful tool for design and drawing of limit gauges by actual applications. The output drawings from this system are in good agreement with the drawings and data of the concerned standards and regulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1996.10a
• /
• pp.71-76
• /
• 1996

스트레인 게이지 브리지와 한개의 진동변위 탐촉자를 이용하여 평판의 근접장에서 음향 인텐시티를 측정하는 방법에 대하여 설명하였다. 또한 구조감쇠의 모델링을 통하여 음향방사파워에 대한 내부손실파워의 비를 나타내는 계수를 정의하여 내부손실파워의 정도를 평가하는 척도로 사용할 수 있음을 설명하였다. 임의의 경계조건을 가지는 평판에서 2개의 마이크로폰과 1개의 가속계를 이용하여 근사적으로 측정된 음향 인텐시티와 본고에서 제시한 방법으로 측정한 음향 인텐시티가 거의 일치함을 보이므로써 제시된 측정방법의 타당성을 검증하였다. 실험에 사용된 계(system)는 일반적인 해석에서 유체부하를 무시할 수 있는 계로 평판내부의 에너지 흐름에 비하여 외부로 방사되는 소음의 에너지 흐름이 매우 작기 때문에 평판내부의 에너지 흐름으로부터 방사되는 소음의 에너지 흐름을 알아내는 것이 매우 어려울 것으로 예상되었으나 본고에 제시된 방법으로 좋은 결과를 얻을 수 있었다. 앞으로 본 방법의 측정 오차에 대한 면밀한 고찰이 있어야 할 것이다. 그리고 평판의 내부손실이 비교적 큰 경우에 본 방법의 실험적으로 검증이 필요할 것이다. 또한 실질적인 문제에 응용되어 얼마만큼 유용한 정보를 제공할 것인가를 살펴보아야 할 것이다.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.25 no.5
• /
• pp.356-361
• /
• 2005

A temperature-compensating double fiber Bragg grating(FBG) sensor having two different FBGs in one fiber line was proposed for real time measurement of mechanical normal strain in structures. Measurement of mechanical strains of the aluminum beam surface by the double FBG sensor was performed under various thermal conditions, and the results were compared with those of electrical resistance strain gage. The FBG sensor fabricated in this study was able to measure accurately the mechanical strains without containing any thermal strain component.

• Science of Emotion and Sensibility
• /
• v.25 no.3
• /
• pp.77-90
• /
• 2022

This study seeks to develop a stretch sensor for measuring the wrist movements of people using fishing lures. In order to confirm wrist movement, a stretch sensor was attached to the wrist band, and measurements of the dorsiflexion, plantar flexion, and fishing landing motion were measured using a scale to gauge factor, tensile strength, and elongation recovery rate. A conductive sensor using CNT dispersion was developed and applied to the E-band under the same conditions. A total of 15 sensors of the same size and five types of impregnation once, twice, and three times each were used to measure the gauge factor using UTM. The sensor that was impregnated twice had the best gauge rate, and the prototypes were manufactured with three sensors with high gauge rates and tensile strength. The results of the operation test conducted by connecting to the Arduino showed that Sample 1, which had the highest tensile strength and gauge factor, had a stable graph wavelength in three operations. Samples 2 and 3 showed stable wavelengths in the dorsiflexion and the plantar flexion; however, signal noise appeared in the fishing landing motion. This showed stable wavelengths in the two motions, but the wavelengths of the graphs differ depending on the tensile strength and gauge factor in the fishing landing motion. As a result, it was possible to identify the conditions necessary for manufacturing a stretch sensor for measuring wrist movement. This study will contribute to the development of smart wearable products for lure fishing.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.2
• /
• pp.453-461
• /
• 2010

This paper presents a branch prediction algorithm and a 4-way set-associative cache for performance improvement of embedded RISC core and a clock-gating algorithm using ODC (Observability Don't Care) operation to improve the power consumption of the core. The branch prediction algorithm has a structure using BTB(Branch Target Buffer) and 4-way set associative cache has lower miss rate than direct-mapped cache. Pseudo-LRU Policy, which is one of the Line Replacement Policies, is used for decreasing the number of bits that store LRU value. The clock gating algorithm reduces dynamic power consumption. As a result of estimation of performance and dynamic power, the performance of the OpenRISC core applied the proposed architecture is improved about 29% and dynamic power of the core using Chartered $0.18{\mu}m$ technology library is reduced by 16%.