• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.7 s.124
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• pp.649-661
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• 2007

Friction-type reinforcing members(FRM) to enhance the resistance to wind loads of a transmission tower through both stiffness strengthening and damping increase are energy dissipation devices that utilize bending deflection of a tower leg. In this paper, the hysteretic behavior of the transmission tower structure with FRMs was experimentally investigated through cyclic loading tests on a half scale substructure model. Firstly, the variation of friction forces and durability of the FRM depending on the type of friction-inducing materials used in the FRM were examined by performing the cyclic loading tests on the FRM. Secondly, cyclic loading tests of a half-scale two-dimensional substructure model of a transmission tower with FRMs were conducted. Test results show that the FRM, of which desired maximum friction force is easily regulated by adjusting the amplitude of the torque applied to the bolts, have stable hysteretic behaviors and it is found that there exists the optimum torque depending on a design load by investigating the amount of energy dissipation of the FRMs according to the increase of torque.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.568-577
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• 2007

Friction-type reinforcing members (FRM) to enhance the resistance to wind loads of a transmission tower through both stiffness strengthening and damping increase are energy dissipation devices that utilize bending deflection of a tower leg. In this paper, the hysteretic behavior of the transmission tower structure with FRMs was experimentally investigated through cyclic loading tests on a half scale substructure model. Firstly, the variation of friction forces and durability of the FRM depending on the type of Friction-inducing materials used in the FRM were examined by performing the cyclic loading tests on the FRM. Secondly, Cyclic loading tests of a half-scale two-dimensional substructure model of a transmission tower with FRMs were conducted. Test results show that the FRM, of which desired maximum friction force is easily regulated by adjusting the amplitude of the torque applied to the bolts, have stable hysteretic behaviors and it is found that there exists the optimum torque depending on a design load by investigating the amount of energy dissipation of the FRMs according to the increase of torque.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.5
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• pp.77-86
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• 2010

Hydrologic Simulation Program-Fortran (HSPF) coupled with PEST which is optimization program was calibrated and validated at Bochung watershed by using monitoring data of water quantities and nutrient loading. Although the calibrated data were limited, model parameters of each land use type were optimized and coefficient of determinations were ranged from 0.94 to 0.99 for runoff, from 0.89 to 1.00 for TN loading, and from 0.92 to 1.00 for TP loading. The optimized hydrological parameters indicated that the forested land could retain rainfall within soil layer with high soil layer depth and infiltration rate compared with other land use type. Hydrological characteristics of paddy rice field are low infiltration rate and coefficient of roughness. The calibrated parameters related to nutrient loading indicated generation of nutrient pollution from agricultural area including upland and paddy rice field higher than other land use type resulting from fertilizer application. Overall PEST program is useful tool to calibrate HSPF automatically without consuming time and efforts.

• Computers and Concrete
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• v.25 no.2
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• pp.95-109
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• 2020

This paper aims to analytically study the effect of loading conditions and confinement type on the mechanical properties of the concrete-steel composite columns under axial compressive loading. The axial loading is applied to the composite columns in the two ways; only on the concrete core, and on the concrete core and steel tube simultaneously, which are called steel tube-confined concrete (STCC) and concrete-filled steel tube (CFST) columns, respectively. In addition, the confinement is investigated in the three types of passive, short-term active and long-term active confinement. Nonlinear finite element 3D models for analyzing these columns are developed using the ABAQUS program, and then these models are verified with respect to the recent experimental results reported by the authors on the STCC and CFST columns experiencing active and passive confinements. Axial and lateral stress-strain curves as well as the failure mode for qualitative verification, and compressive strength for quantitative verification are considered. It is found that there is a good consistency between the finite element analysis results and the experimental ones. In addition, a parametric study is performed to evaluate the effect of axial loading type, prestressing ratio, concrete compressive strength and steel tube diameter-to-wall thickness ratio on the compressive behavior of the composite columns. Finally, the compressive strength results of CFST specimens obtained via the finite element analysis are compared with the values specified by the international codes and standards including EC4, CSA, ACI-318, and AISC, with the results showing that ACI-318 and AISC underestimate the compressive strength of the composite columns, while EC4 and CSA codes present overestimated values.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.313-318
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• 1999

This study is aim to evaluate of the flexure toughness of fiber reinforced concrete with ring type steel fiber. The experiment proceeding ASTM C 78 is performed to make a comparision between the ring type flber and the double-hook type fiber which is recently come in to use. The size of the test specimen is 10$\times$10$\times$35mm and the flexture test is proceeded by third-point loading method. The test lasts until 2mm deflection and the loading speed is 0.01mm/min by deflection control. From the experimental results, the specimens with ring type fiber of 30kg/㎥ and 30mm diameter of ring circle show much higher toughness indices than those of the double-hook type fiber of 30kg/㎥ and 30mm long.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.487-490
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• 2004

In this paper, we investigated the characteristics of initiation and propagation behavior for fatigue crack observed by changing various shapes of initial crack and magnitudes of loading in modified compact tension shear(CTS) specimen subjected to shear loading. In the low-loading condition, the secondary fatigue crack was created in the notch root due to friction on the pre-crack face grew to a main crack. In the high-loading condition, fatigue crack under shear loading propagated branching from the pre-crack tip. Influenced by the shear loading condition, fatigue crack propagation retardation appeared in the initial propagation region due to the reduction of crack driving force and friction on crack face. In both cases, however, fatigue cracks grew in tensile mode type. The propagation path of fatigue crack under the Mode II loading was 70 degree angle from the initial crack regardless of its shape and load magnitude.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.6
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• pp.467-473
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• 2008

This study is to investigate the influence of catalyst loading quantity on the direct methanol fuel cell (DMFC) performance. In this paper, Pt-Ru and Pt-black loading as the catalyst were varied from 1 to $4mg/cm^2$ at the anode and cathode, respectively. The experiment was conducted with single fuel cell consisted of $5cm^2$ effective electrode area, serpentine type flow pattern and Nafion 117 membrane. Also, AC impedance and methanol crossover current were measured to investigate the performance loss precisely. As a result, the performance of fuel cell was significantly increased with the increase of cathode catalyst loading. However, the performance did not increase further above a certain Pt-Ru catalyst loading as the increase of anode catalyst loading.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.302-307
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• 2004

This paper reviewed characteristics of fatigue crack behavior observed by changing various shapes of initial crack and magnitudes of loading in compact tension shear(CTS) specimen subjected to shear loading. In the high-loading condition, fatigue crack under shear loading propagated branching from the pre-crack tip. Meanwhile, the secondary fatigue crack in the low-loading condition which was created in the notch root due to friction on the pre-crack face grew to a main crack. Influenced by the mode II loading condition, fatigue crack propagation retardation appeared in the initial propagation region due to the reduction of crack driving force and friction on crack face. In both cases, however, fatigue cracks grew in tensile mode type. Propagation path of fatigue crack under the shear loading was 70 degree angle from the initial crack regardless of its shape and load magnitude.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.7 no.1
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• pp.21-24
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• 2001

This study was carried out to analyze the effects of packaging units and loading types in agricultural products(apple, pear, and sweet persimmon) palletization. In apple and pear packaging, an optimum loading type was pin wheel loading, and load effective corrugated box dimension was $330{\times}220{\times}170mmm(L{\times}W{\times}H)$ in 5 and 10kg packaging units, but in case of pear box was 10mm higher than apple box. However, in sweet persimmon packaging, block loading was available, and box dimension of $365{\times}275{\times}180mm(L{\times}W{\times}H)$ was the most effective to palletize.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.1
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• pp.11-17
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• 2020

This study conducted a case study and a questionnaire analysis in parallel. In the case study, a study was conducted on domestic manufacturer A by analyzing pallet loading efficiency of RRP(Retail Ready Packaging) products and pallet loading efficiency of MWC(Membership Wholesale Club) delivered products. As a result of the pallet loading efficiency simulation of 50 RRP products of Manufacturer A, it was 80.0% based on the T-11 type pallet and 84.3% based on the T-12 type pallet. It was found It refers that the route of producing the product from the manufacturer A and delivering it to the MWC A in the form of RRP resulted in the decrease of the pallet loading efficiency through the change of the loading pattern and the adjustment of the number of loads. As a result of analyzing the questionnaire about whether the overall efficiency of the supply chain will be improved if the operation of the packaging system considering the SCM(Supply Chain Management) aspect is χ² = 178.500, there was a statistically significant difference at the significance level of 0.000. Manufacturers and logistics companies answered "yes" the most, but distributors answered "is average" the most, confirming that the packaging can be constructed with the highest operational efficiency. Therefore, as a result of confirming the impact of packaging design considering the SCM aspect on logistics efficiency, it indicates the importance of closer collaboration between manufacturers and distributors.