• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.739-743
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• 2007

In this paper, a stereoscopic display system using a rotary disk type beam shutter and two beam projectors is proposed. It is a kind of active stereoscopic display and can be easily converted from passive stereoscopic system using polarizing filters. If it is possible to synchronize the revolution speed of the beam shutter with the integer multiple of the scanning frequency of the beam projectors, we can obtain a comparable performance with our system to an active stereoscopic system using one expensive high performance beam projector. Further, if we rotate the beam shutter at sufficiently high revolution speed, our active stereoscopic system works regardless of synchronization and thus the system is much easier to implement.

• KIEAE Journal
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• v.8 no.1
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• pp.93-98
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• 2008

As high rise buildings and large span spatial structures are constructed, new composite members and construction techniques are continuously developed. Wide flange steel beam can be easily constructed but the fire proofing protection is necessary and the cost is high. Nowadays environmental pollution of structures is becoming a big issue. The material of fire proofing protection is not allowed to use for structural members in several countries because it cab be a cause of environment pollution. Composite beam is a new hybrid beam system which is not needed a fire proofing protection process. Composite beam has better construction capacity than that of RC system and has more economic advantages than that of wide flange steel beam. In this paper, structural design guide lines of composite beam were provided to apply design and construction.

• Journal of Ocean Engineering and Technology
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• v.7 no.1
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• pp.107-113
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• 1993

Sidescan sonar uses the fan type beam which has horizontally narrow and vertically somewhat wide beam pattern. To construct such a beam we will use an array of transducers. In case of using single transducer it must have a high frequency to have the fan type beam, but in case of using an array it must have to be high frequency. We are planning to use 30 kHz transducers for our sidescan sonar under development. This paper shows ways of designing a narrow beam for the sidescan sonar system by illustrating various shapes of the beam patterns.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.6
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• pp.321-327
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• 2019

Spectral Beam Combining (SBC) is used for a high-power fiber laser in order to overcome the power limitation of single fiber laser. In SBC, several laser bwams with different wavelengths are combined to obtain a single-aperture beam by diffraction grating. The combining efficiency is dependent on a linewidth, beam quality and specific wavelength of each beam among others. In this paper, we consider the method of a wavelength monitoring and a feedback control of laser diodes used as seeds of laser beams to obtain optimum combining conditions. In order to measure the wavelengths of multi-beam, we use the high resolution camera and diffraction grating with 1,800l/mm. The experiment results show the possibility of feedback control of a current and temperature of multi-seed laser diodes to obtain optimum wavelengths for SBC.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.513-528
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• 2020

This paper presents the results of an experimental study on the residual behavior of reinforced recycled aggregate concrete (RRAC) beam-columns after exposure to elevated temperatures. Two parameters were considered in this test: (a) recycled coarse aggregate (RCA) replacement percentages (i.e. 0, 30, 50, 70 and 100%); (b) high temperatures (i.e. 20, 200, 400, 600, and 800℃). A total of 25 RRAC short columns and 32 RRAC beams were conducted and subjected to different high temperatures for 1 h. After cooling down to ambient temperature, the following basic physical and mechanical properties were then tested and discussed: (a) surface change and mass loss ratio; (b) strength of recycled aggregate concrete (RAC) and steel subjected to elevated temperatures; (c) bearing capacity of beam-columns; (d) load-deformation curve. According to the test results, the law of performance degradation of RRAC beam-columns after exposure to high temperatures is analyzed. Finally, introducing the influence coefficient of RCA replacement percentage and high temperatures, respectively, to correct the calculation formulas of bearing capacity of beam-columns in Chinese Standard, and then the residual bearing capacity of RRAC beam-columns subjected elevated temperatures is calculated according to the modified formulas, the calculated results are in good agreement with the experimental results.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.446-449
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• 1997

The use of high strength concrete in the fabrication and construction of prestressed concrete beam bridges can result in the increase of girder spacings for standard shapes, as well as the increase of span lengths. The increase of girder spacings corresponds to the reduction of the required number of girders. This study shows that the use of high strength concrete make prestressed concrete beam bridges the economical alternative to any other bridge types. Also, this study has the purpose of giving aids to design of prestressed concrete beam. To achieve this purpose this study provides the plots resulting from research on relationships between the concrete strength of prestressed concrete beam, girder spacing and the number of strands in various span lengths.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.157-162
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• 2003

An experimental investigation was conducted to study the behavior of high-strength RC wide beam-column joints with slab subjected to reversed cyclic loads under constant axial load. Six half scale interior wide beam-column assemblies representing a portion of a frame subjected to simulated seismic loading were tested, including three specimens without slab and three specimens with slab. The primary variables were compressive strength of concrete($f_ck$=285, 460kgf/$cm^2$), the ratio of the column-to-beam flexural capacity($M_r$=$\Sigma M_c / \Sigma M_b$ ; 0.77 -2.26), extended length of the column concrete($l_d$ ; 0, 12.5, 30cm), ratio of the column-to-beam width(b/H ; 1.54, 1.67). Test results are shown that (1) the behavior of specimen using high-strength concrete satisfied for required minimum ductile capacity according to increase the compressive strength, (2) the current design code and practice for interior joints(type 2) are apply to the wide beam-high strength concrete column.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.359-359
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• 2011

Many research applications in basic sciences and biology such as protein crystallography require hard x-rays in the range of 3-20 keV with high brightness. A medium energy storage ring as PLS-II with a beam energy of 3 GeV can meet such high photon energies. In-vacuum undulators (IVU) with a period length of 20 mm and a peak field of 0.97 T are used in the PLS-II ring to produce such X-rays in the fundamental or higher harmonics. Due to the many poles and high fields, insertion devices like wigglers and undulators have a significant impact on the stability of the electron beam with potential degradation of beam quality and life time. Therefore, nonlinear fields must be determined by measurement and evaluated as to their impact on beam stability. Specifically, transverse field roll-off can be a serious detriment to injection in top-up mode and must be corrected. We use magnetic field measurement data to evaluated beam stability by tracking particles using an explicit symplectic integrator in both, transverse and longitudinal planes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.202-205
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• 2009

Tubular torsion beam of high strength steel is going about in an automotive rear axle due to the advantages of light weight and efficient rear packaging capability. High strength tubular beam can be manufactured by the hydroforming in order to ensure dimensional accuracy, while a conventional stamping has been used for steel tubular beam. Internal pressure, feeding and their combination are the key factors of controlling the process. Based on the numerical simulation and try-outs, the optimized hydroforming process conditions for the high strength tubular beam were suggested.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.537-540
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• 1999

The primary objective of this study is to make a contribution to the construction of 40~60 story R/C high rise building by developing the reinforcing details which can improve the seismic performance of high-strength (f'c=700kg/$\textrm{cm}^2$, fy=4000, 8000kg/$\textrm{cm}^2$) R/C beam-column joints. And the purpose of this study is to investigate experimentally the effect of load history on the total energy dissipation capacity of reinforced concrete flexural members. The reinforcing details which can make beam plastic hinging zones moved and spreaded from the column face is proposed to insure the ductile behavior of high-strength RC beam-column joints. The intermediate reinforcement which is horizontally anchored by interlinking each intermediate reinforcements is proposed and tested to examine the mechanical performance of proposed details. Main variables are the shape of the intermediate reinforcements and yield strength of rebars. From the test results, the newly proposed intermediate reinforcement details can move and spread the beam plastic hinging zone about 1.0d from the column face.