• Journal of Radiation Industry
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• v.5 no.1
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• pp.75-80
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• 2011

This study was to determine the microbiological safety and tensile strength of gammairradiated porcine tendon for the development of safe xenografts. Escherichia coli and Bacillus subtilis were used as model pathogens and inoculated as $10^6{\sim}10^7log$ colonies forming unit $(CFU)g^{-1}$. As model virus from porcine, porcine parvovirus (PPV), bovine viral diarrhoea virus (BVDV) and poliovirus were inoculated as $10^5{\sim}10^6$ tissue culture infectious dose $(TCID)_{50}g^{-1}$ into porcine skin. The $D_{10}$ value of E. coli and B. subtilis was measured as $0.32{\pm}0.082kGy$ and $4.0{\pm}0.312kGy$, respectively. Additionally, the $D_{10}$ values of PPV, BVDV and poliovirus were also shown as $1.75{\pm}0.131kGy$, $3.70{\pm}0.212kGy$ and $6.26{\pm}0.332kGy$, respectively. Gamma irradiation decreased the tensile strength of porcine tendon. Results indicate that microbiological safety of porcine tendon can be improved significantly by gamma irradiation. However, further studies are needed to improve the tensile strength of gamma-irradiated porcine tendon.

• Journal of Korea Foundry Society
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• v.20 no.5
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• pp.307-315
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• 2000

The effects of additional elements on the mechanical properties of HSLA cast steels such as hardness, tensile strength and charily impact energy have been investigated. Test results showed the mechanical properties of HSLA cast steels were superior to those of C-Mn cast steels. In case of the HSLA cast steels, HSLA cast steels with all addition of Nb, V, and Ti had more excellent tensile strength than those with individual addition of Nb, V, or Ti. The tensile strengths of HSLA cast steels were increased as the Mo contents were increased from 0.25% to 0.5%. These are attributed to the solution hardening and the change of the precipitation kinetics of NbC due to increased Mo contents. The tensile strength of HSLA cast steel was remarkablely increased as the manganese contents were increased from 0.65% to 1.2% and 1.5%, respectively. However, the optimum composition of HSLA cast steels to obtain the best compromise between tensile strength and charily impact energy compared to C-Mn cast steel was the additions of0.1% C and 1.2% Mn.

• Journal of Welding and Joining
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• v.32 no.6
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• pp.56-63
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• 2014

To develop and understand dissimilar metals joining of Stainless steel and Copper, ultra-high speed laser lap welding was studied using single mode fiber laser in this study. SUS304 and Cu have large differences in materials properties, and Cu and Fe have no intermetallic compounds by typical binary phase of Cu and Fe system. In this study, ultra-high speed lap welds of SUS304 and Cu dissimilar metals using single-mode fiber laser was generated, and weldability of the weld fusion zone was evaluated using a tensile shear test. To understand the phenomenon of tensile shear load, weld fusion zone of interface weld area and fracture parts after tensile shear test were observed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analysis system. And it was confirmed that Cu was easily melting and penetrating in the grain boundaries of SUS304 because of low melting temperature. And high thermal conductivity of copper occurred dissipate heat energy rapidly. These properties cause the solidification cracking in weld zone.

• International Journal of Concrete Structures and Materials
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• v.10 no.sup3
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• pp.97-108
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• 2016

When the energy performance of concrete is substantially higher than that of normal type concrete, such concrete is regarded as energy efficient concrete (WBSCSD 2009). An experimental study was conducted to investigate mechanical properties of energy efficient concrete with binary, ternary and quaternary admixture at different curing ages. Slump test for workability and air content test were performed on fresh concretes. Compressive strength, splitting tensile strength were made on hardened concrete specimens. The mechanical properties of concrete were compared with predicted values by ACI 363R-84 Code, NZS 3101-95 Code, CSA A23.3-94 Code, CEB-FIP Model, EN 1991, EC 2-02, AIJ Code, JSCE Code, and KCI Code. The use of silica fume increased the compressive strengths, splitting tensile strengths, modulus of elasticities and Poisson's ratios. On the other hand, the compressive strength and splitting tensile strength decreased with increasing fly ash.

• Journal of Institute of Convergence Technology
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• v.7 no.1
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• pp.7-10
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• 2017

In general, the shoe stretcher is utilized to stretching the leather of shoe upper in the longitudinal direction. In the capstone design class, we tried to make a shoe leather stretcher for the ball of foot. Since a natural cow leather was recovered in length according to relaxation time after stretched, it was difficult to predict the initial amount of set up of stretching. In this paper, tensile and relaxation experiments were conducted in order to predict the amount of initial stretching for appropriate tensile length. Apparatus of leather stretching was designed and strains of leather were measured according to relaxation times of 12, 18, 24 hours after stretching of 24 hours. It was revealed that the ratio of the final relaxed strain and the initial applied strain was about 0.404 with R-square of 0.990 for a shoe cow leather.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.6
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• pp.356-364
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• 2004

The hydrides in cladding affect the corrosion and tensile properties. In this study corrosion and tensile properties were evaluated with varying the hydrogen concentration. The charged hydrogen contents were ranged from 200 to 1000 ppm. The corrosion rate in water and LiOH solution increases with the hydrogen concentration. The hydride did not affect the corrosion mechanism in the pre-transition region, but in the post-transition region the corrosion rate was accelerated. Cladding E contained higher Niobium content was slowly accelerated compared with other claddings. The yield and ultimate strengths were independent on the hydrogen content. However, the total elongation decreased gradually with increasing the hydrogen content. SEM observation of fracture surface showed that an average of depth of voids decreased with increasing the hydrogen content and small secondary crack are observed.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.93-100
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• 2011

This study deals with the high frequency induction hardening (HF at $850^{\circ}C$, 120kHz & 50kW condition) SM45C steel. (1) The HF specimen, which was tempered at $150^{\circ}C$, did not show any tempering effect. A brittle fracture occurred at rounded area of the tensile specimen. AE (acoustic emission) amplitude distribution showed between 45dB and 60dB. (2) A slip and fracture occurred at the hole area of the HF specimen which was tempered at $300^{\circ}C$. As they pass the yield point, the AE energy is increased intermittently and AE amplitude distribution exists between 70dB and 85dB. In addition, after imposing the maximum tensile load, AE signals showed high amplitude and energy distribution. The AE amplitude showed between 45dB and 70dB. (3) A brittle fracture occurred at HF specimen which was tempered at $450^{\circ}C$ as if it is torn in the direction of $45^{\circ}$ on parallel area over the both sides of the tensile specimen, which lead to several peak appeared in AE energy. It was found that the AE amplitude was relatively low and the AE energy was high.

• Structural Engineering and Mechanics
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• v.77 no.1
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• pp.103-114
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• 2021

Ultra high strength concrete (UHSC) originally proposed by Richards and Cheyrezy (1995) composed of cement, silica fume, quartz sand, quartz powder, steel fibers, superplasticizer etc. Later, other ingredients such as fly ash, GGBS, metakaoline, copper slag, fine aggregate of different sizes have been added to original UHSC. In the present investigation, the combined effect of coarse aggregate (6mm - 10mm) and steel fibers (0.50%, 1.0% and 1.5%) has been studied on UHSC mixes to evaluate mechanical and fracture properties. Compressive strength, split tensile strength and modulus of elasticity were determined for the three UHSC mixes. Size dependent fracture energy was evaluated by using RILEM work of fracture and size independent fracture energy was evaluated by using (i) RILEM work of fracture with tail correction to load - deflection plot (ii) boundary effect method. The constitutive relationship between the residual stress carrying capacity (σ) and the corresponding crack opening (w) has been constructed in an inverse manner based on the concept of a non-linear hinge from the load-crack mouth opening plots of notched three-point bend beams. It was found that (i) the size independent fracture energy obtained by using above two approaches yielded similar value and (ii) tensile stress increases with the increase of % of fibers. These two fracture properties will be very much useful for the analysis of cracked concrete structural components.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4481-4490
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• 2022

In this study, a new rupture disk corrosion test (RDCT) method was developed for real-time detection of stress corrosion cracking (SCC) initiation of Alloy 600 in a primary water environment of pressurized water reactors. In the RDCT method, one side of a disk specimen was exposed to a simulated primary water at high temperature and pressure while the other side was maintained at ambient pressure, inducing a dome-shaped deformation and tensile stress on the specimen. When SCC occurs in the primary water environment, it leads to the specimen rupture or water leakage through the specimen, which can be detected in real-time using a pressure gauge. The tensile stress applied to the disk specimen was calculated using a finite element analysis. The tensile stress was calculated to increase as the specimen thickness decreased. The SCC initiation time of the specimen was evaluated by the RDCT method, from which result it was found that the crack initiation time decreased with the decrease of specimen thickness owing to the increase of applied stress. After the SCC initiation test, many cracks were observed on the specimen surface in an intergranular fracture mode, which is a typical characteristic of SCC in the primary water environment.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.307-310
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• 1999

In this panel test, the toughness and post-cracking tensile strength of SFRC(Steel Fiber Reinforced Concrete) measured on 24 panels(size; 60cm $\times$ 60cm $\times$ 10cm) which are the basic characteristics than can determine the load bearing capacity of SFRC are investigated. Those values are calculated using load-deflection curves and load-absorbed energy curves. Post-cracking tensile strength of SFRC in this study are determined by yield line theory. From the test results, it is seen that the higher the volume of steel fiber is, the higher the absorbed energy is.