• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05a
• /
• pp.71-74
• /
• 2005

The increasement in the floor hight may be one of the most significant problem in the use of precast concrete double slab in the multi-story buildings. The modified double-tees including duct space at the ends of slab were considered in this study. The length and thickness of nib of modified double tee was increased to receive the uniform reaction from rectangular beam, while the original PCI dapped one to receive the point load from inverted tee beam to the leg of double tee. Shear tests were performed on the ends of the modified double tees which were designed by strut-tie model. The modified double tees generally show more ductile flexural failure in the long thickened nib. It is concluded that they show superior failure patterns than that of original dapped one with shear failure.

• Journal of the Korea Concrete Institute
• /
• v.12 no.6
• /
• pp.75-82
• /
• 2000

Flexural behaviors of two typical architectural precast beam sections ; inverted tee and rectangular - were compared and investigated. The heights of web in inverted tee beams are generally less than half of beam depth in building structures to accomodate the nib of double-tee where the total building height limited considerably. The inverted-tee beams are designed for parking live load - 500kgf/$\m^2$ and market - 1,200kgf/$\m^2$ according to the currently used typical shape in the domestic market building site in Korea. The bottom dimension and area of rectangular beams are same to those of inverted tee beams to compare the flexural behaviors of two beams. These two beams are also reinforced for similar strength. Four flexural tests are performed on two beams. Following results are obtained from the tests; 1) The rectangular beam is simpler in production, transportation, and election, and more economic than the inverted tee beam for these two beams with same dimension and similar strength. 1) The estimations of flexural strength of two beams by Strength Design Method and Strain Compatibility Method is fully complied with the result of tests. However, Strain Compatibility Method is slightly ore accurate than Strength Design Method. 2) Overall deflections of two type beam under the service loads are less than those of the allowable limit in ACI Code provision. 3) The rectangular beam is failed in large deflection (average 12.56mm large) than those of inverted tee beams. 4) The rectangular and inverted tee beams with 6m span develop initial flexural crackings under the 88% of full service loading even though they designed to satisfy the ACI tensile stress limit provisions.

• The Journal of Korean Society for Radiation Therapy
• /
• v.26 no.1
• /
• pp.21-28
• /
• 2014

Purpose : For non-small cell lung cancer, if the treatment volume is large or the total lung volume is small, and the tumor is located in midline of patient's body, total lung dose tends to increase due to tolerance dose of spinal cord. The purpose of this study is to compare and evaluate the total lung dose of three dimensional conformal radiotherapy(3D CRT), intensity modulated radiotherapy(IMRT) and volumetric modulated arc therapy(VMAT) using restricted angle for non-small cell lung cancer patients. Materials and Methods : The treatment plans for four patients, being treated on TrueBeam STx($Varian^{TM}$, USA) with 10 MV and prescribed dose of 60 Gy in 30 fractions, 3D CRT, restricted angle IMRT and VAMT radiotherapy plans were established. Planning target volume(PTV), dose to total lung and spinal cord were evaluated using the dose volume histogram(DVH). Conformity index(CI), homogeneity index(HI), Paddick's index(PCI) for the PTV, $V_{30}$, $V_{20}$, $V_{10}$, $V_5$, mean dose for total lung and maximum dose for spinal cord was assessed. Results : Average value of CI, HI and PCI for PTV was $0.944{\pm}0.009$, $1.106{\pm}0.027$, $1.084{\pm}0.016$ respectively. $V_{20}$ values from 3D CRT, IMRT and VMAT plans were 30.7%, 20.2% and 21.2% for the first patient, 33.0%, 29.2% and 31.5% for second patient, 51.3%, 34.3% and 36.9% for third patient, finally 56.9%, 33.7% and 40.0% for the last patient. It was noticed that the $V_{20}$ was lowest in the IMRT plan using restricted angle. Maximum dose for spinal cord was evaluated to lower than the tolerance dose. Conclusion : For non-small cell lung cancer, IMRT with restricted angle or VMAT could minimize the lung dose and lower the dose to spinal cord below the tolerance level. Considering PTV coverage and tolerance dose to spinal cord, it was possible to obtain IMRT plan with smaller angle and this could result in lower dose to lung when compared to VMAT.

• KCI Concrete Journal
• /
• v.14 no.1
• /
• pp.36-42
• /
• 2002

Flexural behaviors of the two typical precast beam sections (inverted tee and rectangular) for buildings were investigated and compared. The height of web in the inverted tee beam was generally less than half of beam depth to be adapted to that of the nib in the ends of double-tee where the total building height limited considerably. The inverted-tee beams were designed for a parking live load - 500kgf/$m^2$ and a market - 1,200kgf/$m^2$ from the currently used typical shape of a domestic building site in Korea. The area and bottom dimension of rectangular beams were the same as those of inverted tee beams. These woo beams were also reinforced with a similar strength. following results were obtained from the studies above; 1) the rectangular beam is simpler in production, transportation, and erection, and more economic than the inverted tee beam in the construction test for these two beams with a same dimension and a similar strength, 2) all of the beams considered in the tests were generally failed in values close to those of the strength requirements in ACI Provisions. The ratios of test result to calculated value are averaged to 1.04. One rectangular and one inverted tee beams failed in a value only 2-3％ larger than the estimated volue of the Strength Design Methool the results of the Strain Compatibility Method wire slightly more accurate than those of the Strength Design Method, 4) the maximum deflections of all of the beams under the full service loads were less than those of the allowable limit in ACI Code Provisions. The rectangular beams experienced more deflection then inverted tee in the same loading condition and failed with more deflection, and 5) the rectangular and inverted tee beams showed good performances under the condition of service and ultimate loads. However, one inverted tee beams with fm span developed an initial flexural crackings under 88％ of the full service load even though they designed to satisfy the ACI tensile stress limit provisions.

• Journal of the Korea Concrete Institute
• /
• v.25 no.1
• /
• pp.81-90
• /
• 2013

The purpose of this study is to evaluate the horizontal shear strength on the interface between PC and cast-in-place concrete for PC composite beams. Six specimens were tested to examine the structural performance of the horizontal interface with different surface condition and stirrup detailing. Except for SF-291B specimen failed in flexural compression, strengths and deformation capacities of five specimens were determined by horizontal shear failure. Horizontal shear strengths by composite horizontal shear or shear friction in current codes could be used to predict the horizontal shear capacity of the interface for specimens. Also detailing for stirrup by PCI design provision could be used to accomplish the composite action in the interface.

• Journal of Korea Society of Industrial Information Systems
• /
• v.23 no.4
• /
• pp.23-31
• /
• 2018

This paper presented the implementation and design of the 2T-2R wireless HD video streaming systems over 1.7 GHz frequency band using 3GPP LTE-TDD standard on NI USRP RIO SDR platform. The baseband of the system used USRP RIO that are stored in Xilinx Kintex-7 chip to implement LTE-TDD transceiver modem, the signal that are transmitted from USRP RIO up or down converts to 1.7 GHz by using self-designed 1.7 GHz RF transceiver modules and it is finally communicated HD video data through self-designed 2x9 sub array antennas. It is that communication method between USRP RIO and Host PC use PCI express x4 to minimize delay of data to transmit and receive. The implemented system show high error vector magnitude performance above 32 dBc and to transmit and receive HD video in experiment environment anywhere. The proposed hybrid beam forming system could be used not only in the future 5G mobile communication systems under 6 GHz frequency band but also in the systems over 6 GHz frequency band like ones in mmWave frequency bands.

• Journal of the Korea Concrete Institute
• /
• v.11 no.6
• /
• pp.57-67
• /
• 1999

Optimization scheme is presented for the design of precast prestressed double-tee beams used as slabs in the parking or market structures. The objective considered is defined by a function that minimizes the hight of the double-tee beam, including the prefabricated element and the concrete topping poured in a second phase. The Sequential Quadratic Programming method is adopted to solve the problem. As an example 12 double-tee beams are designed with the design loads of the current design code of our country. The results from optimization process show that at least 29cm less in overall height than that designed by PCI design handbook. The section determined from the optimization process was refined for practical considerations. A MathCad 7.0 Pro Spreadsheet was prepared to verify all ACI requirements for flexure, shear and deflections. Flexural tests are performed on four full-scale 12.5m prototype models and show that all the specimens are fully comply the flexural strength requirements as specified by ACI 318-95. The present optimization scheme can be used for wider application of the design of precast prestressed double-tee beams with different materials and configurations particularly for in a large scale or for important designs.

• Journal of the Korea Concrete Institute
• /
• v.11 no.3
• /
• pp.141-152
• /
• 1999

Precast prestressed double-tee slab may be designed by the PCI Design Handbook. It is based on the bridge construction and is required for reorganization for the use of buildings in the domestic construction environments. Much enhanced sections are developed from the reforming process on the determined design factors in the previous experimental works on double tees. Pre-determined shape, reinforcement detail, and 5000 psi concrete strength can not be expected as the best solution for the domestic construction requirements because large amount of use on that systems are anticipated. Flexural tests are performed on four full-scale 12.5m proto-type models, "least depth double tee", which are resulted from the optimization process. Domestic superimposed live load regulation, domestic material properties which is available to product, building design requirements and economy in construction are considered as the main factors to establish. the first two sections are double tee section for 1.2 ton/$\m^2$ market live load with straight and one-point depressed strands and the second two are for 0.6 ton/$\m^2$ parking live load with those strand types. All of the specimens tested fully comply with the flexural strength requirements as specified by ACI 318-95. However, the research has shown that following improved considerations are needed for better result in practice. The locations and method of connection for the lowest bottom mild bar, connection method between precast and cast-in-place concrete, and dap-end reinforcement are need to be improved.