• Journal of the Korean Wood Science and Technology
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• v.21 no.4
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• pp.73-78
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• 1993

Crystal structure of tension, opposite and lateral wood of Platanus orientalis L. were analysed in some aspects of crystallinity index, crystallite size, d-spacing of (200) and (004), and integrated intensity ratios with X-ray diffraction method. Crystallinity index and crystallite width in tension wood appeared somewhat larger than opposite or lateral wood. However, d-spacing and integrated intensity ratios were nearly identical irrespective of tension, opposite, and lateral wood.

• Journal of Biosystems Engineering
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• v.36 no.5
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• pp.348-354
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• 2011

Various crop spacing methods have been implemented so far for the greenhouse and plant factory applications. However, there is no generally accepted parameter for evaluation of plant spacing efficiency in plant production system. In this study, 'Planted Area Index' (PAI) of a spacing method is defined as the ratio of the planted area in the field to required planted area using the spacing method when no transplanting operation is assumed. Three common types of spacing methods for plane placement of the plants were modeled mathematically. For calculating the planted area, an optimal growth radius function (R(t)) is needed. Function of the days after transplanting stage gives a radius of an optimal circle area for the living plants. A computer simulation was developed to calculate the PAI, based on three crop spacing methods and four optimal growth radius functions. In general, the 1-D zigzag spacing showed the best PAI. Moreover, it gives an example on how to apply the PAI for the design.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.9
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• pp.645-651
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• 2008

For a high speed train driving at 300 km/h, aero-acoustic noise is a dominant component among various noise sources. The aeroacoustic noise is mainly due to inter-coach spacings because discontinuities in the train surface significantly disturb turbulent flows. This often leads to the uncomfortableness of passengers. Interestingly, the aero-acoustic noise reduces with decreasing the mud-flap spacing of the inter-couch spacing. We perform numerical simulations to investigate flow characteristics around the inter-coach spacing. We model the inter-coach spacing as a simple 2-D cavity with flaps, and calculate the velocity and pressure field using two equation turbulence models, varying the flap spacing. The results show that a wider flap spacing develops a higher inflection point in mean velocity profiles over the cavity. It is likely that large eddies generated near the inflection point persist longer in the downstream since they are less affected by the wall. This probably induces the more aero-acoustic noises. The wider spacing also results in the larger pressure difference between the inside and outside of the cavity. This is also responsible for the increased noise since the large difference would cause a strong flow oscillations in and out of the cavity.

• Journal of the Korean GEO-environmental Society
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• v.10 no.5
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• pp.69-73
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• 2009

In this study, three dimensional numerical analyses were performed with variation of pile spacing (S=3D, 4D, 5D) to compare the behaviour of single pile and pile group with cap in granite soil. In order to compare and analyze the lateral resistance of single pile and pile group by changing pile spacing, the pile group with array of $1{\times}3$ was employed. To reduce the computation time the symmetric boundary condition was used. And Druker-Prager model and elasticity model were used for granite soil and for concrete pile and cap, respectively. Using the analyses results of pile group in granite soil under lateral loading, p-y curve for pile group and single pile with changing pile spacing was drawn. With p-y curve p-multiplier was evaluated. As a result of analysis, the value of p-multiplier was increased with increasing pile spacing under 1.0 due to pile shadow effects.

• International Journal of Concrete Structures and Materials
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• v.10 no.2
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• pp.177-188
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• 2016

One of the primary concerns about the design aspects is that how to deal with the shear reinforcement in the ultra-high performance fiber reinforced concrete (UHPFRC) beam. This study aims to investigate the shear behavior of UHPFRC rectangular cross sectional beams with fiber volume fraction of 1.5 % considering a spacing of shear reinforcement. Shear tests for simply supported UHPFRC beams were performed. Test results showed that the steel fibers substantially improved of the shear resistance of the UHPFRC beams. Also, shear reinforcement had a synergetic effect on enhancement of ductility. Even though the spacing of shear reinforcement exceeds the spacing limit recommended by current design codes (ACI 318-14), shear strength of UHPFRC beam was noticeably greater than current design codes. Therefore, the spacing limit of 0.75d can be allowed for UHPFRC beams.

• Computers and Concrete
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• v.17 no.2
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• pp.227-240
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• 2016

An analytical study was conducted to investigate the effect of the shape and spacing of modified inclined studs used as shear connector between concrete and steel plate on the cyclic behavior of steel plate concrete (SC) shear wall. 9 different analysis cases were adopted to determine the optimized shape and spacing of stud. As the results, the skeleton curves were obtained from the load-displacement hysteresis curves, and the ultimate and yielding strengths were increased as the spacing of studs decrease. In addition, the strength of inclined studs is shown to be bigger compared to that of conventional studs. The damping ratios increased as the decrease of stiffness ratio. Finally, with decreasing the spacing distance of studs, the cumulative dissipated energy was increased and the seismic performance was improved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.227-228
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• 2006

In order to calculate the maximum undeformed chip thickness in grinding operation, it is necessary to estimate the successive cutting point spacing. In the past it is obtained by experiments. In this paper, the average successive cutting point spacing has been estimated using the given grinding input conditions.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.5
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• pp.305-311
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• 2019

In this study, we examined the proper spacing between the expansion joints according to the temperature load of the inter-modal terminal platform infrastructure to implement a new inter-modal automated freight transport system, which we intend to introduce in Korea. To review the proper expansion joint spacing of the terminal platforms, we set the maximum expansion joint spacing according to the regional temperature changes using the equation proposed by the Federal Construction Council (FCC) of the United States. Then, the maximum displacement value, which was calculated through the structural analysis program, and the limit of the horizontal displacement of the building structure were compared. The proper expansion joint spacing was selected as the slab length at which the maximum displacement of the structure, due to temperature changes, was below the horizontal displacement limit. Based on the application of maximum expansion joint spacing for each region calculated through the FCC's suggestion, the maximum displacement that could occur within the limit of the lateral displacement of the structure was determined.

• Structural Engineering and Mechanics
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• v.87 no.4
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• pp.333-346
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• 2023

This paper presents findings from an experimental study that was focused on evaluating the use of Forta-Ferro (FF) and Polyvinyl Alcohol (PVA) fibers on the response of moderate and special ductility beams under load cycles. For this reason, eight full-scale specimens, identical in geometry, were subjected to gradual cyclic loading. The specimens included two plain concrete beams with medium and special ductility, three beams with medium ductility and stirrup spacing of one-quarter the effective depth (d/4) and three beams with special ductility, and stirrup spacing of one-half the effective depth (d/2), strengthened with FF and PVA fibers separately. The use of fibers was aimed at reducing the amount of shear reinforcement in flexural members. Here, the variation of parameters including the maximum strength, ultimate strength, stiffness, ductility, damage index, energy dissipation, and equivalent damping was studied. Utilizing FF and PVA fibers improved the performance in beams with moderate ductility when compared to those beams with special ductility. Therefore, in special ductility beams, fibers can be used instead of crossties and in moderate ductility beams, fibers can be added to reduce the ratio of shear reinforcement. Furthermore, increasing the stirrup spacing in the moderate ductility beams from d/4 to d/2 and adding 0.6% FF or 1.5% PVA fibers resulted in behavior similar to those of the moderate ductility beam.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.17-22
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• 2018

Multilayer mirrors are optical elements that can replace single crystal optical elements such as silicon or germanium, and they have artificial diffraction plane of a thickness of several nanometers. We examined the first Bragg angle and the reduction of reflectivity by variation of layer thickness in a W/Si multilayer mirror of small d-spacing. A W/Si multilayer mirror for an incidence angle of $0.55^{\circ}$ and an energy of 17.5 keV was designed and showed a maximum reflectivity of 72.67%. When the thickness of tungsten or silicon layer was simultaneously changed, the first Bragg angle was shifted and the reflectivity was reduced. When there was a change in thickness for one layer of W/Si multilayer, no change in the reflectivity was showed but the unevenness of the envelope was observed. Reduction of reflectivity was also observed at random Gaussian thickness variations. It is possible to predict the tolerance of multilayer mirror by examining the reflectivity degradation according to the thickness change in the W/Si multilayer mirror of small d-spacing.