• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.634-636
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• 2007

• Journal of Korean Society of Steel Construction
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• v.25 no.1
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• pp.61-70
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• 2013

A turn-buckle is capable of adjusting the tensile force by left-hand threads and right-hand threads between tension members. There are different types of turn-buckles according to tension member and connection form but the practical and existing turn-buckles are incapable of measuring the tensile force. A turn-buckle for adjusting and measuring tensile force has therefore been developed. This study shows the ultimate strength and reliability for measurement of the new turn-buckles through finite element analysis of the developed ones. From analytic results of the new turn-buckles which have the measurement limit loads of 100kN, 200kN and 300kN, the ultimate strength is approximately five times stronger than the measurement limit capacity. Additionally, a review of the new turn-buckle, which has the measurement limit load of over 300kN, shows that there is a tendency for the size of turn-buckle to become larger. So the connection devices were designed and the loading test was conducted from the concept that the parallel connection of turn-buckle with 300kN capacity can measure the tensile force of 600kN. The results of parallel loading test show the sufficient possibility. Furthermore, the mock-up test was constructed to investigate the release of initial load and corrosion when the new turn-buckle is installed at the outdoor and exposed to rain and atmosphere.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.92-95
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• 2019

In this paper, a novel laser-based non-contact and non-destructive stress measurement technique is newly proposed for measuring stress in steel structural members. As the demand of stress monitoring in structural members is increased, various non-destructive techniques are being applied to the field of structural health monitoring. Spectroscopic techniques are non-contact technique and widely used for chemical identification of target materials. Especially, piezospectroscopic technique is a residual stress measurement technique in thermal barrier coatings. Although the piezospectroscopic technique has high possibility of measuring structural stress in steel members, the technique has been rarely applied to this field. In this paper, piezospectroscopy-based stress measurement technique is, therefore, proposed for measuring stress in steel structural member. To do that, alumina particles have been coated onto a specimen of a structural steel rod using a thermal spray coating technique. And then, an uniaxial compression test has been conducted to the specimen to collect each fluorescence spectrum under different loading conditions. Finally, the linear relation of spectral shift and applied compressive stress of the specimen has been experimentally established.

• Journal of IKEEE
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• v.24 no.1
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• pp.33-39
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• 2020

In this paper, we propose the design technique of the vehicle's load weight measuring system using tire pressure, which is one of the physical elements of tires. The proposed technique consists of four processes: noise correction by load and vibration, gas flow correction, data mixer and weight conversion. Noise correction by load and vibration eliminates noise that increases the tire's internal pressure due to external shocks and vibrations produced by the vehicle while it is in motion. In the gas flow correction process, the noise of the internal pressure of the tire is increased due to the temperature rise of the ground with respect to the data obtained through the noise correction process due to the load and vibration. In the data mixer process, the load and pressure on the tolerances the empty, median and the full load are classified according to the change in pressure of the tire that is delivered perpendicular to the tire in the event of cargo. In the weight conversion process, weight is expressed by weight through weight conversion algorithms using noise correction results by load and vibration and gas flow correction. The weight conversion algorithm calculates the weight conversion factor, which is the slope of the linear function with respect to the load and pressure change, and converts the weight. In order to evaluate the accuracy of the loading weight measurement system of the vehicle using the tire pneumatic system technique proposed in this paper, we propose the design technique of the vehicle's load weight measuring system using tire pressure, which is one of the physical elements of tires.. Noise correction results by load and vibration and gas flow data correction results showed reliable results. In addition, repeated weight precision test showed better weight accuracy than the standard value of 90% of domestic companies.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.8
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• pp.1493-1502
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• 1992

The purpose of this study is to identify the effects of loading variables on fatigue crack opening behavior, using structural steel SS41. To use various stress ratios, three kinds of the methods varying stress ratio were used; .DELTA.P const., P$_{max}$ const., and P$_{min}$ const.. To measure the opening load, the direct measuring method which measures the distance between two micro indentations 20 .mu.m behind crack tip and the elastic compliance method were used. As the results of present study, the following conclusions are obtained. First, using the direct measuring method, it was possible to measure the COD at any location behind crack tip. Second, as measuring point becomes farther from crack tip, opening load becomes smaller. Third, the acceleration of da/dN near notch is due to crack opening behavior. Finally, opening ratio is a function of not only R, but .DELTA.K.K.K.

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.3
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• pp.200-206
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• 1999

This paper describes the stress analysis of a curved beam by using photoelasticity. In order to measure accurate isochromatic fringe orders at certain locations. fringes are doubled and sharpened by digital image processing. After fringe multiplication and sharpening. fringe orders can be read as a quarter order interval (N=0, 1/4, 2/4, 3/4,...). The results obtained from photoelastic experiment are compared with those calculated by using theory. Two results are agreed well even though there are some scatter bands with maximum 8 percent for the results of photoelastic measurements and theoretical calculation. Difference may be occurred due to the slight misalignment of the direction to which axial load is applied in photoelastic experiment. It is confirmed that accurate measurement of stress distribution can be possible by using the techniques of fringe multiplication and sharpening in photoelasticity.

• Proceedings of the ESK Conference
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• 1994.04a
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• pp.105-105
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• 1994

신체 부위를 이용한 Manual Materials handling(MMH) 작업시 무리한 작업하중의 취급으로 인하 여 많은 사고 또는 요통이 발생하기 때문에 작업자의 능력에 맞는 적정 하중에 대한 연구가 필요 하다. MMH작업의 적정하중에관한 연구는 미국 등의 나라에서는 많이 이루어져 왔으나 우리나라에서 는 연구되어 있지 않다. 미국의 경우 NIOSH Guideline을 만들어 MMH시 작업지침으로 활용하고 있으 나 이 지침을 그대로 우리나라에 적용하기에는 신체조건이 달라 우리나라 고유의 연구가 필요하겠다. 적정하중의 연구에는 많은 시간과 경비가 필요하기 때문에 외국의 경우 심리 육체적방법(Psychophysical Method)을 사용하여 시간과 경비를 줄이고도 실제 8시간 작업시의 결과와 비슷한 결과를 얻었다. 본 연구에서는 MMH작업의 적정 하중결정에 있어서 심리육체적 방법을 사용하여 한국인 작업자에 대한 하중과 HIOSH Guideline의 RWL값과의 비교를 하였다. 학생군과 실제 작업자군의 피실험자에 대하여 심리육체적 방법을 적용하여 들기작업을 실험하였다. 6가지 들기 작업을 20분 동안 실시하여 피실험자들이 자신에게 적합하다고 생각하는 적정하중을 측정하였다. 그 결과, 학생군은 RWL값보다 평균 2.5배를, 작업자군은 3.4 배를 적정하중으로 정하였다. 따라서 HIOSH Guideline을 적용한 RWL값은 우리나라 작업자에게는 많은 여유가 있는 하중임을 보여 주었다.

• Computational Structural Engineering
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• v.3 no.2
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• pp.109-115
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• 1990

The probabilistic characteristics of wind loads have been analyzed using statistical data on wind speeds, pressure coefficient, exposure coefficient, and gust factor. The wind speed data collected at 25 nationwide weather stations have been modified to be consistent in measuring height, exposure condition as well as averaging time. Having performed Monte Carlo simulation for various heights and site conditions, the statistical models of wind loads were determined, in which Type-I extreme value distribution has been applied. The models also incorporate a reduction factor of 0.85 to account for the reduced probability that the maximum wind speed will occur in a direction most unfavorable to the response of structure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.2
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• pp.75-82
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• 2022

Nondestructive method to predict buckling load for the propellant tank of launch vehicle should be evaluated. Vibration correlation technique can predict the global buckling load of unstiffened cylindrical structure with geometric initial imperfection using correlation of natural frequency and compressive load from compressive test below the buckling load. In this study, vibration and buckling tests of a thin metal unstiffened propellant tank model subjected to internal pressure and compressive loads were performed and the test results were used for VCT to predict global buckling load. For the vibration test of thin structure, non-contact excitation method using a speaker was used. The response was measured with piezoelectric polymer(PVDF) sensor. Prediction results of VCT were compared with the measured buckling load in the test and the nondestructive global buckling load prediction method was verified.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1996.04a
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• pp.108-116
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• 1996

본 논문에서는 하중부와 방법을 추(dead weight)와 공압(pneumatic)을 이용한 방법에서 스프링을 이용한 방법을 추가하였으며, 압축형 스프링을 선택적으로 사용하여 마찰시험기 수직방향에서의 강성을 큰 변화 폭으로 변화시켰다. 또한 선행된 연구를 통하여 수직하중의 변동량에 크게 영향을 미치는 것으로 알려진 바 있는 디스크 시편의 misaligment 효과를 상사하고 극대화 하기 위하여 본 논문에서는 경사진 디스크 시편을 추가로 사용하였다. 상기조건으로 마찰시험기 시스템의 각 하중부과 방법과 수직강성 변화가 마찰특성에 미치는 영향을 실험적으로 측정 평가하였으며, 마찰시험기 동특성계 모델의 이론적 해석을 통하여 마찰특성 변화를 고찰하였다. 또한, 미끄럼 접촉 시의 수직력과 마찰력을 측정하고, 데이터의 통계적 처리방법에 따른 마찰계수의 변화 특성도 평가하였다.