• Journal of the Korean Wood Science and Technology
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• v.36 no.3
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• pp.1-8
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• 2008

The lateral strength test of bending type was done to investigate the lateral capacity of the double bolt connection of domestic larix glulam according to bolt spacing. In the shear specimen, which is bolted connection in the inserted plate type, the hole of bolt was made, changing the diameter of bolt (12 mm and 16 mm), the number of bolt (single bolt : control and double bolt), the direction of bolt row (in parallel to grain : Type-A and in perpendicular to grain : Type-B) and the bolt spacing (Type-A : 4 d and 7 d and Type-B : 3 d and 5 d). Lateral capacity and failure mode of bolt connection were compared according to conditions. In prototype design (KBCS, 2000), the reduction factor of the allowable shear resistance that the bolt spacing is reduced was calculated. The results were as follows. 1) Bearing stress per bolt in the single and double bolt connection of Type-A was directly proportional to bolt diameter and bolt spacing. Bearing stress of Type-B decreased as bolt diameter was increased, and decreased by 2~10% when bolt diameter was increased. 2) In the single bolt connection and the double bolt connection of Type-A, the splitted failure was formed in the edge direction. When the bolt spacing was 3 d in Type-B, bolt was yielded more in the part of tension than in the part of compression, and the splitted failure started at the bolt in the part of tension. In the 5 d spacing specimen, the bolt in the part of tension was yielded similarly to bolt in the part of compression, and the splitted failure started in the part of compression. 3) In the prototype design, the reduction factor was calculated by non-dimensionizing the yielding load in the standard of bolt spacing (Type A : 7 d and Type B : 5 d). In 12 mm bolt connection, the reduction factor of bolt spacing 4 d (type-A) and single bolt connection was 0.87 and 0.55, respectively, and the reduction factor of bolt spacing 3 d (Type-B) and single bolt connection was 0.91 and 0.55, respectively. In 16 mm bolt connection, the reduction factor of bolt spacing 4 d (type-A) and single bolt connection was 0.96 and 0.76, respectively, and the reduction factor of bolt spacing 3 d (Type-B) and single bolt connection was 0.91 and 0.77, respectively.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.1
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• pp.81-90
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• 2008

It is of great importance to determine the optimum cutter spacing in TBM. In order to determine the optimum cutter spacing, a series of cutting tests by linear cutting machine (LCM) are performed with changing cutter space. This study showed that a numerical method for estimating the optimum cutter spacing could be developed by AUTODYN-3D in order to overcome the limitation of LCM test. By using this method, the optimum cutter spacing of Hwangdeung granite was estimated.

• International Journal of Ocean System Engineering
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• v.4 no.1
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• pp.1-18
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• 2014

Heave plates have been widely used to enhance viscous damping and thus reduces the heave response of Spar platforms. Single heave plate attached to the keel of the Spar has been reported in literature (Tao and Cai 2004). The effect of double heave plates on hydrodynamic response in random waves has been investigated in this study. The influence of relative spacing $L_d/D_d$ ($D_d$-the diameter of the heave plate) on the hydrodynamic response in random waves has been simulated in wave basin experiments and numerical model. The experimental investigation has been carried out using 1:100 scale model of Spar with double heave plates in random waves for different relative spacing and varying wave period. The influence of relative spacing between the heave plates on the motion responses of Spar are evaluated and presented. Numerical investigation has been carried out to investigate effect of relative spacing on hydrodynamic characteristics such as heave added mass and hydrodynamic responses. The measured results were compared with those obtained from numerical simulation and found to be in good agreement. Experimental and numerical simulation shows that the damping coefficient and added mass does not increase for relative spacing of 0.4 and the effect greater than relative spacing on significant heave response is insignificant.

• Applied Microscopy
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• v.33 no.3
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• pp.195-204
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• 2003

The Experimental calibration method has been investigated to correct d-spacing estimation and to identify phases in the electron diffraction data acquired by imaging plates. When the diffraction data from the imaging plate was corrected by the d-spacing calibration method with the radial intensity distribution plotting in this experiment, The accuracy of d-spacing estimation was significantly increased in errors of about 0.5%. The experimental calibration equation followed up the first order exponential decay function was derived from the trace of d-spacing deviation between the measured and the calculated values. It was applied to the analysis of d-spacing and the phase identification of the transitional phases formed from [001] gibbsite specimen by electron beam irradiation effect. In this case more accurate phase identification and d-spacing evaluation is possible for the transitional phases whose diffraction patterns are complicatedly superimposed. It is concluded that ${\chi}$-alumina, ${\gamma}$-alumina and ${\sigma}$-alumina are clearly identified as the major transitional phases formed from gibbsite by electron beam irradiation for 120 min.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.117-129
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• 2000

This paper discusses the lateral behavior of group pile in homogeneous and non- homogeneous (two layered) soil. In the group pile, the model tests were to investigate the effects on spacing-to-diameter ratio of pile, pile array, ratio of pile spacing, constraint condition of pile tip, eccentric load and ground condition. The group efficiency and lateral deflection induced in active piles were found to be highly dependent on the spacing-to-diameter ratio of pile, number of pile. Lateral bearing capacities in the group piles of fixed tip, in the case of 6D spacing and $3\times3$ array, were 40-100% higher than those in the group pile of free tip. Based on the results obtained, a spacing-to-diameter of 6.0 seems to be large enough to eliminate the group effect for the case of relative density of 61.8% and 32.8%, and then each pile in such a case behaves essentially the same as a single pile. However, in the case of dense sand, it can be estimated that a spacing-to-diameter of 8.0 seems to be large enough to eliminate the group effect. In this study the group efficiency is illustrated in experimental function with spacing-to-diameter, S/D, relative density and number of pile. The distribution of shear force in lead row piles, in the case of 3$\times$3 array group pile, was 41.6-52.4% for 3D spacing and 34-40% for 6D spacing, respectively. The shadowing effect for the parallel direction of lateral loading appears to be more significant than the one for the perpendicular direction of lateral loading.

• Journal of the Korean Geotechnical Society
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• v.27 no.8
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• pp.39-50
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• 2011

This study was conducted to analyze the thermal behavior of a PHC energy pi1e system in saturated soil conditions, various seasonal and flow-speed conditions during 100 hours of operation through numerical analysis. The examination was a1so conducted with a single pile as well as with group pils. For the operation of 100 hours, the average heat exchange rate appeared 55 W/m, 47 W/m during winter and summer respectively. An increase in flow-speed was associated with a rise in the heat exchange rate. And thermal behavior analysis results during winter season show that thermal efficiency has increased when there are more free thermal planes. For the operation in group pile as 3D and 5D pile spacing (D: pile diameter), average heat exchange rate increased as pile spacing grows. Compared with the heat exchange rate of single pile, thermal exchange efficiency of group pile decreased by 89% (for 3D spacing) and 93% (for 5D spacing).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4759-4780
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• 2017

Full Dimension multiple input multiple output (FD-MIMO) architecture employs a planar array design at the Base Station (BS) to provide high order multi-user MIMO (MU-MIMO) via simultaneous data transmission to large number of users. With FD-MIMO, the BS can also adjust the beam direction in both elevation and azimuth direction to concentrate the energy on the user of interests while minimizing the interference leakage to co-scheduled users in the same cell or users in the neighboring cells. In a typical highly populated macrocell environment, modelling the elevation angular characteristics of three-dimensional (3D) channel is critical to understanding the performance limits of the FD-MIMO system. In this paper, we study the throughput performance of FD-MIMO system with varying elevation angular spread and inter-element spacing using a 3D spatial channel model. Our results show that for a typical urban scenario, horizontal beamforming with correlated antenna spacing achieves optimal performance but by restricting the spread of elevation angles of departure, elevation beamforming achieves high array gain with wide inter-element spacing. We also realize significant gains due to spatial array processing via modelling the elevation domain and varying the inter-element spacing for both the transmitter and receiver.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.48-54
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• 2004

The effects of injector spacing s and injector diameter d on mixing are numerically investigated in supersonic combustor with perpendicular injection behind a backward-facing step. Simulations are reported for airstream Mach number of 2.4. Parameters are changed on following 4 cases to investigate the effects of injector configuration on mixing efficiency $\eta_m$. In the case of varying d or s, dynamic pressure ratio $Rq(=(pu^2)_j/(pu^2)_a)$ is also varied to keep bulk equivalence ratio $\Phi({\oe})Rq.d^2/s)$ constant. (l) Injector spacing s is varied at constant $\Phi$=0.5, 1, 2 for injector diameter d=6mm. In the case of $\Phi$=1, $\eta_m$ has its maximum value at s=24mm. The reason is that increase of $\eta_m$. , by widening spacing at Rq=constant competes with decrease of $\eta_m$ by increasing Rq at s=constant. When spacing is narrow, the flow field of vicinity of injector becomes two-dimensional because adjacent jets interferes each other. By widening spacing, air is easily entrained by three-dimensional effect. This mechanism also appears in the case of $\Phi$=0.5, 2 for d=6mm, and $\eta_m$. reaches its maximum value at s=24mm for $\Phi$=0.5 and at s=42mm for $\Phi$=2. (2) In the case of injector diameter d varied at $\Phi$=1 for s=30mm, $\eta_m$. has its maximum value at d=3mm. The reason is that decrease of $\eta_m$ by increasing injector diameter competes with increase of $\eta_m$ by decreasing Rq at d=constant.(3) In the case of s varied at $\Phi$=0.5, 1,2 for d=3mm, the injector spacing at which mixing efficiency has its maximum value is s= 18mm for $\Phi$=0.5, s=24mm for $\Phi$=1, s=24mm for $\Phi$=2. Therefore it is found that d=3mm and s=24mm can be optimum configuration over a range of $\Phi$=0.5~2.(4) The effect of h on the optimum spacing is investigated. s is varied for d=6mm at step height h=4, 6, 8mm. The simulation results do not show significant change on the step height.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.753-756
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• 2005

Rapid prototyping (RP) technologies are mainly performed by layered manufacturing (LM) process which manufactures 3D physical objects by depositing 2D sections in a direction. Thus, deformations are apt to occur in overhanging area of the RP processed part. Also, excessive adhesion between part and platform of the RP apparatus is generated. In order to prevent these problems, most of the RP technologies adopt support structure. Main element to support a part in the support structure is strand. In actual field, however, the number of strand is determined by the software operating reference guide or RP system operator's experience. In this paper, a methodology to determine the optimal strand spacing is presented through experiments and measurements for the SL part deformation by change of strand spacing and part weight in the support structure of the stereolithography.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1125-1130
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• 2005

This paper presents a method for inter-sheet spacing control in a flexible media handling device. In order to verify the performance of inter-sheet spacing control by experiment, system of section structure is introduced in the first place. In the introduced system, each section is driven by different servo motor for independent section freedom. And suitable inter-sheet spacing control algorithm that is more optimal than conventional inter-sheet spacing control algorithm is proposed. Finally experiments are performed to confirm the performance of inter-sheet spacing control. And two inter-sheet spacing control algorithms, conventional and proposed, are compared with each other.