• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.13-16
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• 2008

In a tension-controlled section, all steel tension reinforcement is assumed to yield at ultimate when using the strength design method to calculate the nominal flexural strength of members with steel reinforcement arranged in multiple layers. Therefore, the tension force is assumed to act at the centroid of the reinforcement with a magnitude equal to the area of tension reinforcement times the yield strength of steel. Because FRP materials have no plastic region, the stress in each reinforcement layer will vary depending on its distance from the neutral axis. Similarly, if different types of FRP bars are used to reinforce the same member, the stress level in each bar type will vary, and the member will show different behavior from our expectation. In this study, six high-strength concrete beam specimens reinforced with conventional steels, CFRP bars, and GFRP bars as flexural reinforcements were constructed and tested. The members reinforced with hybrid reinforcements showed higher stiffness, smaller crack width, and better ductility than the members reinforced with single type of FRP bars.

• Food Science of Animal Resources
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• v.25 no.3
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• pp.304-309
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• 2005

This study was performed to investigate the effect of rearing period(45 and 70 days) on the changes of the yield, physical trait and the composition of fatty acids. The average weight of 100 duck meat at 45 days post hatch was 2.2kg. The yield of meats from prime cuts of 2.1kg, which are the most consumed today, was composed to whole legs($14.1\%$), wings($8.7\%$) and breast(12.5\%$). The ratio of whole legs and breast was similar, In the secondary cuts, the meats was consisted in drumstick($12.5\%$), thigh($7.3\%$), breast($11.7\%$), tender lion($0.8\%$), drum matte($4.9\%$) and wing($2.6\%$). Especially, the drumstick was twice higher than the wing. The content of oleic acid was 50.87 to $51.32\%$ and 49.84 to $50.03\%$ in the breasts and leg, respectively. In the breast, meat at 75 days the oleic acid was slightly increased DHA was not detected in the breast meat, However, it was $0.13\%$ in the leg. The $a^{*}$ value in meat color, ranged was 16.67 to 17.92 in the breast and 15.81 to 17.15 in the leg. Statistically, there was no significantly difference between the breast and leg. The cooking loss of the breast and leg was $26.37\%\;and\;30.32\%$, respectively. The shear force value was $2.20\;kg/0.5inch^2$ at 45 and $2.84\;kg/0.5inch^2$ at 75 days post hatchet respectively. Therefore, the raring period was effect on the shear force value, but not on the cooking loss and meat color.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.10a
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• pp.133-138
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• 1991

The aim of the present paper is to develop a computer program predicting ultimate fracture strength of initially cracked structure under monotonically increasing external loads. For this purpose, two kinds of 3-D isoparametric solid elements, one 6-node wedge element and another 8-node brick element are formulated along the small deformation theory. Plasticity in the element is checked using von Mises' yield criterion. Elasto-plastic stiffness matrix of the element is calculated taking account of strain hardening effect. If the principal strain at crack tip which is one nodal point exceeds the critical strain dependin on the material property, crack tip is supposed to be opened and the crack tip node which was previously constrained in the direction perpendicular to the crack line is released. After that, the crack lay be propagated to the adjacent node. Once a crack tip node is fractured, the energy of the newly fractured node should be released which is to be absorbed by the remaining part. The accumulated reaction force which was carried by the newly fractured node so far is then applied in the opposite direction. During the action of crack tip relief force, since unloading may be occured in the plastic element, unloading check should be made. If a plastic element unloads, elastic stress-strain equation is used in the calculation of the stiffness matrix of the element, while for a loading element, elasto-plastic stress-strain equation is continuously used. Verification of the computer program is made comparing with the experimental results for center cracked panel subjected to uniform tensile load. Also some factors affecting ultimate fracture strength of initially cracked plate are investigated. It is concluded that the computer program developed here gives an accurate solution and becomes useful tool for predicting ultimate fracture load of initially cracked structural system under monotonically increasing external loads.

• Korean Journal of Social Welfare
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• v.41
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• pp.119-146
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• 2000

The goals and strategies of welfare-to-work (WTW) policies have been sources of contentious political debate. In the United States, despite 20 years of welfare reform, there remain important differences of opinion regarding how best to design and deliver WTW programs. The proliferation of state and local WTW experiments has led to the identification of two ideal-types of WTW programs: the Labor Force Attachment and Human Capital Development models. Most of the recent policy debate about WTW in America has focused on the relative merits and performance of LFA and HCD. While the Primary goal of the LFA model is for welfare recipients to achieve a rapid transition into work, the HCD model seeks to improve the long-term employability of welfare dependents through education and skill development. LFA policies tend to be strongly outcome-oriented and generally can yield quick results. Their "any job is a good job" philosophy has proved attractive to policy-makers who are anxious to see concrete results in a short-term period. In contrast, the HCD policies do not simply dump welfare dependents at the bottom of the labor market, but aim to secure relatively stable and well-paid jobs. However, these strengths are offset by several practical weaknesses including high unit costs and long-term investment in human capital. In recent years, LFA policies have been increasingly favored by both policy officials and politicians in the United States. The introduction of Temporaray Assistance to Needy Families of 1996 has been accelerating the trend. What is going to happen to welfare recipients? This simple shift to the LFA model, however, will only see an alarming increase of working poor in a near future.

• Journal of Animal Science and Technology
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• v.62 no.4
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• pp.553-564
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• 2020

The present study investigated the effects of duck skin gelatin and carrageenan on the quality of semi-dried restructured jerky. Restructured jerky was prepared as follows: G0 (control, without duck skin gelatin and carrageenan), G0C (0.3% carrageenan), G0.5 (0.5% duck skin gelatin), G0.5C (0.5% duck skin gelatin and 0.3% carrageenan), G1 (1.0% duck skin gelatin), and G1C (1.0% duck skin gelatin and 0.3% carrageenan). The moisture content was the highest for the semi-dried restructured jerky from G0.5C and G1C groups, which showed the lowest for shear force value (p < 0.05). The processing yield of semi-dried restructured jerky with carrageenan was higher compared to that of the control group (p < 0.05). The rehydration capacities of G0.5, G0.5C, and G1C groups were significantly higher than the rehydration capacity of the control group (p < 0.05). Water activity, lightness, yellowness, flavor score, texture score, and overall acceptability were the highest (p < 0.05) for the semi-dried restructured jerky from the G1C group. No significant (p > 0.05) difference was observed in appearance score among restructured jerky prepared from duck skin gelatin and carrageenan. Thus, the addition of 1.0% duck skin gelatin and 0.3% carrageenan to semi-dried restructured jerky formulations results in the optimization of quality characteristics.

• Journal of Korean Society of Steel Construction
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• v.24 no.1
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• pp.35-46
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• 2012

With the increase in the demand for high-rise buildings, the use of high-strength steel has likewise increased. Thus, it has become more necessary to study the resistance force of the high-strength hollow structural section (HSS) joint of 600MPa. Additionally, the current design equation in Korea limits maximum yield stress at 360MPa in the case of HSS. In other words, since the current specification does not apply to HSS of 600MPa, this study aims to investigate the applicability of design equations as well as examine the behavior of the connection through the experiment and finite element analysis (FEA) of the plate-tube connection of 600MPa. In particular, this paper presents the behavior of joints with the gusset plates welded in the longitudinal direction of the circular hollow section (CHS) when the joints are subjected to lateral force. Comparing design equations with the results of FEA and the test, existing design equations are underestimated to be 56~79% in the case of high-strength materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.380-388
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• 2016

Commercially pure titanium (CP Ti) has been actively used in plate heat exchangers due to its light weight, high specific strength, and excellent corrosion resistance. However, compared with automotive steels and aluminum alloys, there has not been much research on the plastic deformation characteristics and press formability of CP Ti sheet. In this study, the mechanical properties of CP Ti sheet are clarified in relation to press formability, including anisotropic properties and the stress-strain relation. The flow curve of the true stress-true strain relation is fitted well by the Kim-Tuan hardening equation rather than the Voce and Swift models. The forming limit curve (FLC) of CP Ti sheet was experimentally evaluated as a criterion for press formability by punch stretching tests. Analytical predictions were also made via Hora's modified maximum force criterion. The predicted FLC with the Kim-Tuan hardening model and an appropriate yield function shows good correlation with the experimental results of the punch stretching test.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.77-82
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• 2010

This study evaluated the characteristics and reliability of an auger crane with a built-in hydraulic extender. The field test of the hydraulic extender was performed with the hydraulic lines filled with hydraulic fluid and free of air. The pressure generated during the test was measured with a digital pressure gauge. The crane was considered to have undergone one cycle of the excavation process after it had performed excavation under three conditions at the same location. This process was performed three times in total. From the results of the excavation using the hydraulic extender, it was found that the maximum pressure and torque measured were 19.9 [MPa] and 895.4 [$kgf{\cdot}m$], respectively. The rotation force of the auger crane generated at this time signifies a horizontal force. If the excavation diameter of the auger crane is increased, the rotation speed is reduced causing the circumferential speed to also be reduced. The torsional shear stress of the extendable auger crane was calculated to be approximately 23.5 [MPa]. However, the rotation shaft material used for this system was carbon steel for machine structural use (SM45C). Since the minimum torsional yield stress is greater than 150 [MPa] according to KS D 3752, it means the equipment has secured a safety factor greater than 6. Therefore, it was found that when performing work using the extendable auger crane, it exhibited no problems with the safety and reliability of its shaft.

• Geomechanics and Engineering
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• v.7 no.3
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• pp.263-277
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• 2014

In the conventional design of retaining structures in a seismic zone, seismic inertia forces are commonly assumed to act upwards and towards the wall facing to cause a maximum active thrust or act upwards and towards the backfill to cause a minimum passive resistance. However, under certain circumstances this design approach might underestimate the dynamic active thrust or overestimate the dynamic passive resistance acting on a rigid retaining structure. In this study, a new analytical method for dynamic active and passive forces in c-${\phi}$ soils with an infinite slope was proposed based on the Rankine earth pressure theory and the Mohr-Coulomb yield criterion, to investigate the influence of seismic inertia force directions on the total active and passive forces. Four combinations of seismic acceleration with both vertical (upwards or downwards) and horizontal (towards the wall or backfill) directions, were considered. A series of dimensionless dynamic active and passive force charts were developed to evaluate the key influence factors, such as backfill inclination ${\beta}$, dimensionless cohesion $c/{\gamma}H$, friction angle ${\phi}$, horizontal and vertical seismic coefficients, $k _h$ and $k_v$. A comparative study shows that a combination of downward and towards-the-wall seismic inertia forces causes a maximum active thrust while a combination of upward and towards-the-wall seismic inertia forces causes a minimum passive resistance. This finding is recommended for use in the design of retaining structures in a seismic zone.

• Steel and Composite Structures
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• v.36 no.2
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• pp.119-141
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• 2020

In this paper, wavy square absorbers were experimentally and numerically investigated. Numerical simulations were performed with LS-Dyna software on 36 wavy absorbers and their crushing properties were extracted and compared with the simple one. The effect of different parameters, including wave height, wave depth, and wave type; either internal or external on the crushing characteristics were also investigated. To experimentally create corrugation to validate the numerical results, a set of steel mandrel and matrix along with press machines were used. Since the initial specimens were brittle, they were subjected to heat treatment and annealing to gain the required ductility for forming with mandrel and matrix. The annealing of aluminum shells resulted in a 76%increase in ultimate strain and a 60% and 56% decrease in yield and ultimate stresses, respectively. The results showed that with increasing half-wave height in wavy square absorbers, the maximum force was first reduced and then increased. It was also found that in the specimen with constant diameter and half-wave depth, an increment in the half-wave height led to an initial increase in efficiency, followed by a decline. According to the conducted investigations, the lowe maximum force can be observed in the specimen with zero half-wave depth as compared to those having a depth of 1 cm.