• Journal of the Optical Society of Korea
• /
• 제8권4호
• /
• pp.149-155
• /
• 2004

Newly developed modal transmission-line theory(MTLT) is used to analyze rigorously the optical power distribution in grating-assisted directional couplers(GADCs) with three guiding channels. By defining a novel coupling efficiency ${\eta}$ amenable to the rigorous analytical solutions of modal transmission-line theory, we explicitly evaluate the power coupling and distribution of TM modes. The results reveal that the incident power is sensitively partitioned through three output channels in terms of such grating parameters as the grating period, the duty cycle, and the operating wavelength.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2002년도 학술.기술논문발표회
• /
• pp.37-41
• /
• 2002

Lap splice is used in building construction up to recently. As buildings become higher and larger, the use of high tensile bar is increasing due to increasing in the use of high compression concrete. However the using of high tensile bar in lap splice causes eccentricity and difficulty in placing of concrete inside the form, therefore not allowing enough intervening material. Various mechanical connection are being developed but the coupler of today needs either a secondary intervening material or secondary processing that consumes much time. Therefore a coupler, needing neither a secondary intervening material nor secondary processing, was made in this study which lead to following results. (1) Breaking occurred in all experimented rebar. (2) Acquirement of tension exceeding the standard requirement. (3) Acquirement of elongation percentage within the standard requirement.

• Nuclear Engineering and Technology
• /
• 제49권5호
• /
• pp.1071-1078
• /
• 2017

A buncher is one of the main pieces of equipment in the medium energy beam transport line (MEBT) for China accelerator driven sub-critical system (C-ADS) Injector II. To focus the beam longitudinally and match the beam for the acceptance of the superconducting linac section, two room temperature quarter wave resonator (QWR) bunchers with frequency of 162.5 MHz have been designed as parts of the MEBT. According to the beam transmission matching of the MEBT and the geometric parameters requirements of bunchers, the unique mechanical structure and the main processing technology of buncher cavities and their couplers and tuners are described in this paper. The fabrication of bunchers and their parts have been completed and tested at high power, the test results agree well with the design requirements. These bunchers work well for about two years in Institute of Modern Physics, Chinese Academy of Sciences.

• Computers and Concrete
• /
• 제12권2호
• /
• pp.131-149
• /
• 2013

Various types of reinforcement splicing methods have been developed and implemented in reinforced concrete construction projects for achieving the continuity of reinforcements. Due to the complicated reinforcement arrangements and the difficulties in securing bar spacing, the traditional lap splicing method, which has been widely used in reinforced concrete constructions, often shows low constructability and difficulties in quality control. Also, lap spliced regions are likely to be over-reinforced, which may not be desirable in seismic design. On the other hand, mechanical splicing methods can offer simple and clear arrangements of reinforcement. In order to utilize the couplers for the ribbed-deformed bars, however, additional screw processing at the ends of reinforcing bars is typically required, which often lead to performance degradations of reinforced concrete members due to the lack of workmanship in screw processing or in adjusting the length of reinforcing bars. On the contrary, the use of screw-ribbed reinforcements can easily solve these issues on the mechanical splicing methods, because it does not require the screw process on the bar. In this study, the mechanical coupler suitable for the screw-ribbed reinforcements has been developed, in which any gap between the reinforcements and sleeve device can be removed by grouting high-flow inorganic mortar. This study presents the uniaxial tension tests on the screw-ribbed reinforcement with the mechanical sleeve devices and the cyclic loading tests on RC columns with the developed coupler. The test results show that the mechanical sleeve connection developed in this study has an excellent splicing performance, and that it is applicable to reinforced concrete columns with a proper confinement by hoop reinforcement.

• Steel and Composite Structures
• /
• 제36권3호
• /
• pp.321-337
• /
• 2020

Contemporary design and construction of steel-concrete composite structures employs the use of prefabricated concrete elements and demountable shear connectors in order to reduce the construction time and costs and enable dismantling of elements for their potential reuse at the end of life of buildings. Bolted shear connector with mechanical coupler is presented in this paper. The connector is assembled from mechanical coupler and rebar anchor, embedded in concrete, and steel bolt, used for connecting steel to concrete members. The behaviour and ultimate resistance of bolted connector with mechanical coupler in wide and narrow members were analysed based on push-out tests and FE analyses conducted in Abaqus software, with focus on concrete edge breakout and bolt shear failure modes. The effect of concrete strength, concrete edge distance and diameter and strength of bolts on failure modes and shear resistance was analysed. It was demonstrated that premature failure by breakout of concrete edge occurs when connectors are located 100 mm or closer from the edge in low-strength and normal-strength reinforced concrete. Furthermore, the paper presents a relatively simple model for hand calculation of concrete edge breakout resistance when bolted connectors with mechanical coupler are used. The model is based on the modification of prediction model used for cast-in and post-installed anchors loaded parallel to the edge, by implementing equivalent influence length of connector with variable diameter. Good agreement with test and FE results was obtained, thus confirming the validity of the proposed method.

• 소성∙가공
• /
• 제28권3호
• /
• pp.145-153
• /
• 2019

The objective of this study is to analyze the mechanical splicing characteristic of the threaded bar according to the contact conditions of the transverse rib. In order to consider the contact conditions of the rib, selection of the main variables including the gap of the core diameter ($l_c$), rib angle (${\theta}$), and the number of contacts ($C_N$) of transverse rib was done. So as to analyze the splicing characteristic of the D51 threaded bar, a finite element (FE) simulation of the tensile test was conducted using the designed D51 threaded bar and coupler. Through FE simulation results, it was verified that the mechanical slicing characteristics varied based on the main design variables ($l_c$, ${\theta}$, and $C_N$). It was further confirmed that it was important to determine the $C_N$ in consideration of $l_c$. Additionally, the tensile test results of the D25 and D51 threaded bar combined with the couplers were similar to FE simulation results. Furthermore, to quantitatively evaluate FE simulation and test results, the calculation equation for the contacted projection area ratio (R) of the transverse rib was proposed. To secure a mechanical splicing joint of the threaded bar, it was established that the R calculated using the proposed equation had to be greater or equal to 40%.

• 한국안전학회지
• /
• 제31권1호
• /
• pp.41-47
• /
• 2016

The rolling stock is composed of several cars. In order to operate in combination, it is necessary to connect the device, called coupler, between the rolling stocks. When the collision occurs between cars, couplers should be able to absorb the shock. Urban railway has used only rubber absorbers. But recently, the hydraulic buffer has been considered in general railway. In order to know the performance of the buffer it should be conducted to experiments. But whenever this combination change, we should experiments to know a lot of the dynamic behavior of each coupler. These experiments are generally replaced by the simulation, since a lot of time and cost consuming. The quasi-static map of hydraulic buffer obtained by the experiments is required for the simulation. However, the experiments for obtaining such a quasi-static map is costly and time consuming. In this paper, it proposes a method for deriving the quasi-static map of hydraulic buffer from the theoretical model.

• 한국자동차공학회논문집
• /
• 제18권4호
• /
• pp.107-114
• /
• 2010

Coupling systems for trains need more complicated buffer equipments than existing systems because the recent tendency of the regulations enforces trains to be safe for collisions even when the driving speed is higher than before. Using hydraulic buffer is an effective way to satisfy the requirement while it causes the increase of the cost for the coupling system. In this study, we introduce the methodology to build a simulation model for the hydraulic buffer, which could be installed into the coupling systems. In the simulation model of the hydraulic buffer, the reacting force is determined by both buffer stroke and speed whereas the elastic buffer model is designed by using only the buffer stroke in other studies. The simulation results with the advanced hydraulic buffer model shows that the simulating results can be close the real experimental results around 10%, and, if we considers friction forces, the simulation calculates the maximum force within 10% comparing to the experimental.

• 조명전기설비학회논문지
• /
• 제30권2호
• /
• pp.11-19
• /
• 2016

By incorporating a polarization-diversity loop configuration, we have demonstrated the inline switching of transmission and reflection spectra of one of two short-period fiber gratings (SPFGs) with different resonance wavelengths without reconfiguring the filter structure. The proposed filtering apparatus consists of a fiber-pigtailed polarization beam splitter, two SPFGs, and three quarter-wave plates (QWPs). The proposed filter can independently choose the transmission or reflection spectrum of each SPFG through the appropriate adjustment of the orientation angles of the QWPs within the filter without additional optical switches and couplers. The average insertion loss, band rejection ratio, and side-mode suppression ratio of the fabricated filter were measured as ~4.59, ~17.88, and ~19.67dB, respectively.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
• /
• 제61권12호
• /
• pp.705-709
• /
• 2018

It is challenging to achieve sufficient hearing gain in patients with mixed hearing loss. In chronic middle ear diseases, conventional passive reconstructive surgeries often result in suboptimal hearing gain and additional hearing aids may have limitations due to insufficient sound amplification, occlusion effect, acoustic feedback, and skin irritation. Middle ear implantation (MEI) using Vibrant Soundbridge (VSB) is another option for auditory rehabilitation in mixed hearing loss as well as sensorineural hearing loss. The floating mass transducer of VSB can be placed on various middle ear structures either directly or using different types of couplers in order to deliver vibratory mechanical energy to the cochlea. We report a patient who presented with bilateral mixed hearing loss due to chronic otitis media and had limitations using conventional hearing aids in the worse hearing ear. The patient was successfully treated with MEI using the Bell coupler together with middle ear surgery in a single step.