• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.155-163
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• 2008

Experimental study has been performed in order to investigate the behavior of RC beams strengthened with externally bonded post-tensioned CFRP (Carbon Fiber Reinforced Polymer) strips. Specimens consist of 9 small-scaled specimens with the different post-tensioning level as a main test parameter. A control specimen and specimens with simply bonded CFRP strips have been manufactured to compare the structural performances of prestressed system. From the test results, it was observed that the specimens strengthened with simply bonded CFRP strips showed debonding failure below 50% of CFRP tensile strength due to premature debonding. On the other hand, all the specimens strengthened with post- tensioned CFRP strips reached the rupture strength of the CFRP strip. The cracking and yielding loads were also increased proportionally to the post-tensioning level, but the ultimate loads were nearly equal regardless of the post-tensioning level.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.721-730
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• 1998

In this paper, an experimental study have been many studies on the joints of steel structure, for it has great influences on the safety of structures. Research on block shear rupture of the joint receiving pure tension have been done in foreign countries, but not in Korea. This study focuses on the propriety of block shear design code, according to limited state design criteria of steel structures recently established in Korea, by an experiment on the joint of angle tension members. The methods of this study were to compare other study results on block shear rupture mode and ultimate capacity, and to evaluate the propriety of the criteria design code. The result is that tension yield shear ruptures and shear yield tension ruptures happened at the joint, and the experimental rupture load was 15% higher than the capacity entered in the criteria design code. We conclude that it is necessary to revaluate the block shear design code presented by many studies on the limited state design criteria of steel structures.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.37-42
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• 2008

Cable member in structure is tension systems in which the load carrying members transmit loads to support system by tensile stress with no compression or flexure allowed. Cable system have been widely used large span structure roof, air-supported structure, prestressed membrane, cable network roof, suspension structures, guyed tower, ocean platforms, suspension bridges. Cable member can transmit loads by the edge connected system such as socket, swaging, mechanical splice sleave, clip, wedge, loop splice etc. This study will shown an experimental results on the strength of connection socket of cables. In the results of experiment, most of cable connection specimen occurred the failure at the connection socket part before the cable arrived at tensile failure load.

• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.17-24
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• 2018

The pullout test, a nondestructive testing(NDT), for pre-installed inserts is perhaps the most widely used technique to estimate the in-situ compressive strength of concrete. It measures the force needed to pullout a standardized metal insert embedded into concrete members. The pullout test was certified by the American Society for Testing and Materials(ASTM) and Canadian Standards Association(CSA) as a reliable method for determining the strength of concrete in concrete structures under construction. To easily estimate the strength of ultra-high-strength concrete, a simplified pullout tester, primarily composed of a standard 12mm bolt with a groove on the shaft as a break-off bolt, an insert nut, and a hydraulic oil pump without a load cell, was proposed. Four wall and two slab specimens were tested for two levels of concrete strength, 80MPa and 100MPa, using a simplified pullout tester with a load cell to verify the advantages of the pullout test and simplified pullout test. The compressive strength of concrete, pullout load, and the rupture of the break-off bolt were measured 11 times, day 1 to 7, 14, 21, 28, and 90. The correlation of the pullout load and the compressive strength of each specimen show a higher degree of reliability. Therefore, a simplified pullout test can be used to evaluate the in-place strength of ultra-high-strength concrete in structures. The prediction equation for the groove diameter of the break-off bolt(y) with the concrete strength(x) was proposed as y=0.0184x+5.4. The results described in this research confirm the simplified pullout's utility and potential for low cost, simplicity, and convenience.

• Journal of the Korea Convergence Society
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• v.10 no.6
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• pp.281-286
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• 2019

Appearance is a means of competitiveness for modern people, and one of the factors that harms the desires of modern people is white hair. For the modern man who needs to express beautiful appearance to others by covering white moth, we performed hair analysis after white moth hair dye treatment. The maximum modulus and tangential modulus according to the maximum load, maximum tensile strength, maximum elongation, breaking load, fracture strength, elongation at break, and evaluation interval between 1N-3N experimental group and control group of 1N-Respectively. Maximum load, maximum tensile strength, breaking load and breaking strength tended to be larger than those of the control group, while the maximum elongation and breaking elongation were the highest in the control group and the elongation decreased with the experimental group treatment. The maximum modulus and tangential modulus of the 1N-3N test group were higher than those of the control group at 0~0.15 and 0.15~2.5, respectively. Based on the study on the cosmetic changes of the hair before and after the treatment, it can be used as a basic data to select the correct oxidative hair dye product, the proper amount of application and the time to leave.

• Composites Research
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• v.12 no.2
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• pp.53-61
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• 1999

A failure criterion must be considered in each failure mode and loading condition to provide easy determining strength parameters, flexibility and rational simplicity. In this study, new failure criterion was developed by introducing equivalent strength under biaxial loading of tension and torsion. The experimental results showed that the equivalent biaxial strength has a power law relation with respect to a parameter, cos($tan^{-1}R_b$). Failure strength under biaxial loadings could be predicted as a function of tensile strength, torsional strength and biaxial ratio. The scattering of experimental data could be predicted using a Weibull distribution function and the concept of equivalent biaxial strength. Also, in this study, a fatigue theory was developed based on a plane stress model which enabled the S-N curve for combined stress states to be predicted from the S-N data for uniaxial loading. The prediction models can be predicted a biaxial strength and fatigue life of general laminated composite naterials under multi-axial loadings.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.269-275
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• 1981

The fishing hooks were tested for breaking and unbending due to plastic deformation of the material. Study of tensile test is not complicated, but has not even worked out fully enough, especially when the test specimen is subjected to plastic deformation. The fishing hook is subjected to unbending stress and the critical section is a Point which is furthest from the line of action of the forces. The dynamic force of fish during jerks depends on their speed of movement and body weight, the kinetic energy corresponding to it and also on the rlastic displacement of the rigging which absorb the energy. Six kinds of hook were tested by the dynamometer under tensile speed 290mm/min (subscript s) and 780mm/min (subscript f). According to their results, the breaking load(B: kg) can be induced with the formula $B={\alpha}wd^2+\beta$ where w(mm) is the distance between the barb base and the lower shank and d(mm) is diameter. The coefficients of the formula for the round hooks(R) and the angular hooks(A) are approximately as follows: $$R:\;\alpha_{s}=0.5,\;\beta_{s}=1.6,\;\alpha_{f}=0.4,\;\beta_{f}=1.4$$ $$A:\;\alpha_{s}=1.1,\;\beta_{s}=2.0,\;\alpha_{f}=1.0,\;\beta_{f}=0.9$$ The ratio of $B_{f}\;to\;B_{s}$ is corresponding to 0.8. The ratio of deformation(X) that is moved distance of barb base at break to the distance(H) between head base and barb base is about $50\%$. Further study should be carried out on the subject of impact and fatigue test under the same condition which is exerted force by the hooked fish.

• Journal of the KSME
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• v.31 no.3
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• pp.261-266
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• 1991

원자력발전소 배관에 대한 일반적인 파단전누설(LBB)개념 적용절차 및 해석 방법에 대해 간단히 기술하였다. 그러나 LBB해석방법은 배관의 크기 및 작용하중의 상태에 따라 많은 차이가 있 으므로 보다 많은 배관에 LBB개념을 적용하여 설계하기 위해서는 합리적인 해석방법의 마련, 배관재질의 파괴인성치 향상 및 원자력발전소의 운전조건 개선 등을 위한 계속적인 노력이 필요 하리라고 판단된다.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.1
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• pp.51-62
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• 2000

핵연료집합체 검증 프로그램의 일환으로 본 연구에서는 지진과 배과파단이 핵연료집합체의 건선성에 미치는 영향을 검토하였다 원자로 노심의 상세 동적해석을 이용하여 지진 및 배과파단시 핵연료 집합체에 발생하는 전단력 굽힘 모우멘트 및 변위를 계산하였고 또한 집합체를 지지하고 있는 지지격자체의 충격력을 검토하였다 이들 하중에 대한 핵연료집합체의 응력해석을 수행하여 사고조건하에서의 구조적 건전성에 대하여 언급하였고 추후 설계시 고려할 사항을 제시하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.6
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• pp.471-478
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• 2018

Static tests of the composite wing structure were performed to verify damage tolerance design. Both 5 cases of DLLT and 3 cases of DULT were completed to meet requirements for static strength. After inducing BVID and open hole damages on the critical areas of the composite wing based on associated regulations, the DULT and fracture test were performed. In major wing parts, the measured strains and displacements agreed well with those of structural analysis. The initial structural fracture occurred at the area having minimum margin of safety as expected by analysis. As a result, it was confirmed that results from analytic model and strength evaluation were similar to behaviors of the composite wing structure.